physics pahang

- 1 -

SULIT

960/2

SEPTEMBER 2008

PEPERIKSAAN PERCUBAAN

SIJIL TINGGI PELAJARAN MALAYSIA

NEGERI PAHANG DARUL MAKMUR

PHYSICS

PAPER 1

One hour and fourty-five minutes

Instructions to candidates:

DO NOT OPEN THIS BOOKLET UNTIL YOU ARE TOLD TO DO SO.

There are fifty questions in this paper. For each question, four suggested answers are given.

Choose one correct answer and indicate it on the multiple-choice answer sheet provided.

Read the instructions on the multiple-choice answer sheet very carefully.

Answer all questions. Marks will not be deducted for wrong answers.

A Data Booklet is provided.

Arahan kepada calon:

JANGAN BUKA BUKU SOALAN INI SEHINGGA ANDA DIBENARKAN BERBUAT

DEMIKIAN.

Ada lima puluh soalan dalam kertas ini. Bagi setiap soalan, empat cadangan jawapan

diberikan. Pilih satu jawapan yang betul dan tandakan jawapan itupada helaian jawapan aneka

pilihan yang dibekalkan.

Baca arahan pada helaian jawapan aneka pilihan itu dengan teliti.

Jawab semua soalan. Markah tidak akan ditolak bagi jawapan yang salah.

Buku Data dibekalkan.

Pahang Trial STPM 2008 http://edu.joshuatly.com/ http://www.joshuatly.com/

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1. Which of the following errors are systematic errors? A Zero errors B Parallax errors C Errors caused by non-uniformity in shape D Errors caused by changes in the surroundings 2. Which of the following pairs of physical quantities are vectors? A work , momentum B frequency , velocity C displacement , torque D moment of inertia, acceleration 3. The diagram below shows a block of mass m in contact with the ground and is connected to another block of mass 3m by a string through a smooth pulley.

If the block of mass m is released, what will be the speed of the block of mass 3m just before it hits the ground?

A 3

2gh B gh C gh2 D gh6

m

3m

h


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t T

p

0

A

t T

p

0

B

t T

p

0

C

t T

p

0

D

4. A body initially at rest was acted on by a force in the same direction. The magnitude of the force F changes with time t as shown in the diagram below.

Which of the following graphs shows changes in the linear momentum p of the object with time t? 5. A car of mass 1000 kg is moving with a constant speed of 20 m s-1 on a straight horizontal road with an output power of 20 kW. If the output power is suddenly increased to 60 kW, what is the acceleration of the car at this instant?

A 0.2 ms-2 B 0.3 ms-2 C 2.0 ms-2 D 3.0 ms-2

t T

F

0


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6. The diagram below shows a particle moving in a circle with constant speed 3.0 m s-1. The centripetal force is 100 N. The diameter XY of the circle is 2.0 m.

The work done on the particle when it moves through the semicircle XPY is A 0 J B 300 J C 314 J D 628 J 7.The diagram below shows a ball of mass m and radius r moving at a translational speed u and rolling up an inclined plane without sliding. After reaching a height of h , the speed of the ball is v.

If g is the acceleration of free fall and the moment of inertia of the ball about its rotation

axis is 2

3

2mr , which expression is equal to h ?

[The effect of friction is negligible]

A g

vu

3

22 B

g

vu

2

22 C

g

vu

6

)(5 22 D

g

vur

3

)( 222

u

v

h

X Y O

P


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8. A rigid body has rotational kinetic energy of 20 J and angular momentum 10 kg m2 s-1. What is the angular velocity of the body?

A 0.5 rad s-1 B 1.0 rad s-1 C 2.0 rad s-1 D 4.0 rad s-1 9. The diagram shows a system of objects which are at equilibrium. The 10 kg cuboid is almost slipping on the horizontal surface. What is the coefficient of static friction between the cuboid and the horizontal surface?

A 0.29 B 0.50 C 0.71 D 0.87 10. An object of mass m is raised from the earths surface to a height R where R is the radius of the earth. If the mass of the earth is M and the gravitational constant is G, what is the gain in potential energy of the object?

A R

GmM

2 B

R

GmM

2 C

R

GmM D

R

GmM2

11. Which of the following relationships below correctly relates the potential energy U, kinetic energy T and the total energy E of a satellite?

A ETU == B ETU 22 ==

C ETU2

1

2

1==

D ETU2

1==

30o

5kg

10kg


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12.The graph below shows the variation of acceleration a with displacement x of a particle performing a simple harmonic motion.

The frequency of oscillation of the simple harmonic motion is A 0.87 Hz B 1.15Hz C 4.77 Hz D 34.41 Hz 13. Which of the statements below is true regarding damped oscillations systems? A The system does not oscillate at its natural frequency B When resonance occurs, the system does not loose energy C Damping causes the oscillating frequency to decrease D The oscillating amplitude is maximum when the forcing frequency is almost the same

as the natural frequency. 14. Two waves of the same frequency but having amplitudes 2a and 3a respectively

experienced interference. The ratio amplitudeat the point of destructive interference

amplitudeat the point of constructive interference is

A 5

1 B

9

4 C

3

2 D

2

3

15. If the level of intensity of a sound is raised by 10 dB, what is the ratio of the new sound intensity to the original sound intensity? A 0.1 B 1 C 10 D 1010

0.02 -0.02

0.6

-0.6

a/m s-2

x/m


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16.The transverse wave in a string is represented by the equation y = 10 sin [ (x 0.2t)] , where x and y are measured in centimeters and t in seconds. The phase difference between two points 0.2 cm apart on the wave is A 0.11 rad B 0.13 rad C 0.20 rad D 0.63 rad 17. A sound source is moving towards a stationary observer. If the source produces a sound of velocity v and wavelength , what is the velocity and wavelength of the sound detected by the observer? Velocity Wavelength A v B v < C > v < D > v > 18. The graph below shows the change in potential energy U between two atoms of a solid with the separation r of the atoms.

Which of the statements below is true regarding the atoms which are at the state represented by the point X on the graph above? A The absolute temperature is zero B The total energy is zero C The potential energy is zero D The attractive force is maximum

X

U

0 r


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19. Which of the following best shows the stiffness of a solid? A Elastic limit B Youngs modulus C Deformation point D Stress strength 20. The characteristic of a wire when stretched by a force is represented by the stress-strain graph below.

Which of the following is a false deduction from the graph above?

A The permanent deformation of o is obtained when the stress applied at point X is removed.

B Atomic planes in the wire slides over one another when the wire is stretched from X to Y C The shaded area under the graph OW has the same value as the strain energy. D When maximum stress m is applied, the wire begins to thin non-uniformly.

W

X

Y

0

m Stress

Strain o


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21. The graph below shows the change in pressure P with density of an ideal gas at temperature T and 300 K.

What is the temperature T? A 214 K B 254 K C 355 K D 420 K 22.The most probable speed of the oxygen molecule at room temperature is 400 ms-1. Which of the speeds given below, is most likely to be the r.m.s. speed of the oxygen molecules at that temperature? [No calculations required]

A 80 ms-1 B 360 ms-1 C 400 ms-1 D 490 ms-1

23. The degree of freedom of the molecules of an ideal gas is the number of A ways in which the molecules can move randomly B independent ways in which the internal energy of the gas can change C independent ways in which the molecules can gain energy D independent ways in which the gas can expand or be compressed 24. Which of the equations below cannot be used for an adiabatic process of an ideal gas?

A dQ = 0 B pV = RT C T V -1=constant D pV= constant

25. Heat conduction in metals at room temperature is largely caused by A propagation of waves in conductors B absorption of free electrons in conductors C collisions between electrons and atoms D movement of high energy atoms in conductors

300 K

T

2.00 2.80 0 / kg m-3

1.5 x 105

P / Pa


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26 Which one of the following statements is true concerning the strength of the electric

field between two oppositely charged parallel plates? A It is zero midway between the plates. B It is a maximum midway between the plates. C It is a maximum near the positively charged plate. D It is constant between the plates except near the edges.

27 In the diagram shown below, the switch is first connected to P. The switch is then

connected to Q. What is the charge that remains in the 6 F capacitor when the switch is connected to Q?

A 8 C B 12 C C 24 C D 72 C

28 A cell with e.m.f. 6.0 V and internal resistance, r = 2.0 is connected to three

resistors of values 2R, 6R and 6R as shown in the figure below.

If the potential difference across point P and point Q is 3.0 V, what is the value of R? A 1.0 B 2.0 C 3.0 D 4.0

29 Determine the length of a copper wire that has a resistance of 0.172 and cross-sectional area of 1x 10-4 m2. The resistivity of copper is 1.72 x 108 m.

A 10 m B 100 m C 1000 m D 10000 m

P Q

12V 3F 6F

E = 6.0 V r = 2.0

2R

6R

6R

P Q


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30 Two long and parallel straight wires are separated by a distance r in vacuum. An

electric current flows through each wire in the same direction. The magnetic flux density at the mid-point between the two wires is

A r

Io B r 2

Io C r

Io

2 D zero

31 A circular coil consists of 5 loops each of diameter 1.0 m. The coil is placed in an

external magnetic field of 0.5 T. When the coil carries a current of 4.0 A, a torque of magnitude 3.93 N m acts on it.

Determine the angle between the normal to the plane of the coil and the direction of the magnetic field.

A 30o B 45 C 60o D 90

32 A long, straight wire is in the same plane as a rectangular conducting loop. The wire

carries a constant current I as shown in the diagram below. Which one of the following statements is true if the wire is suddenly moved toward the loop?

A There will be no induced e.m.f. and no induced current. B There will be an induced e.m.f. but no induced current. C There will be an induced current that is clockwise around the loop. D There will be an induced current that is counterclockwise around the loop.

33 In an ideal transformer, the most important function of the soft iron core is A to reduce the eddy currents B to improve the flux-linkage between the primary and secondary coils C to dissipate the heat generated by the two coils D to eliminate the back e.m.f. produced in the two coils.

34 An alternating current I = Io sin 200 t is connected to a pure inductor. The variation of the instantaneous power in this circuit with time is

A sinusoidal with frequency 100 Hz. B constant. C sinusoidal with frequency 200 Hz. D sinusoidal with frequency 50 Hz.


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35 What is the function of negative feedback in the operational amplifier? A To increase the input impedance. B To make the amplifier more stable. C To increase the gain. D To make the amplifier into non-inverting. 36 Which one of the following types of wave is intrinsically different from the other four? A sound waves B gamma rays C radio waves D visible light 37 A converging lens of focal length f is placed 0.2 m from an object and an image is

produced on a screen 0.8 m from the lens. With the object and screen fixed, an image of the object can also be formed on the screen by placing a converging lens of focal length

A f at a distance of 0.1 m from the screen B f at a distance of 0.2 m from the screen. C 3f at a distance of 0.1 m from the screen. D 3f at a distance of 0.2 m from the screen.

38 The diagram below shows an air wedge formed by two glass plate. Monochromatic

light of wavelength 600 nm is incident normally on it. Given y = 8.0 cm and separation between dark fringes is 2 mm, determine the value of h.

A. 1.2 x 10-5 m B 1.17 x 10-5 m C 1.50 x 10-6 m D 1.50 x 10-4 m

39 Youngs double slit experiment uses the same light source to illuminate the two slits.

This is necessary to ensure that light coming out from both slits have A the same speed. B a constant phase difference. C the same intensity. D the same frequency.

monochromatic light

glass h

y


- 13 -

40 A ray of light consisting of two wavelengths 1 and 2 (2 > 1) is incident on a piece of diffraction grating. The third order diffraction for 2 superimposes on subsequent order

diffraction image for 1 . What is the ratio of 2

1

?

A 0.5 B 0.75 C 1.3 D 1.5

41 An ultraviolet light source causes the emission of photoelectrons from a zinc plate. A

more intense light source of the same wavelength would give A the same number of photoelectrons each second with the same maximum energy. B the same number of photoelectrons each second with a greater maximum energy. C more photoelectrons each second with the same maximum energy. D more photoelectrons each second with a greater maximum energy. 42 A car with mass m possesses momentum of magnitude p. Which expression correctly

represents the kinetic energy, K, of the car in terms of m and p?

A m

pK

2= B

2

mpK = C

2

2mp

K = D m

pK

2

2

=

43 An electron accelerated from rest through an electric potential of V has a de Broglie

wavelength of . Which of the following graphs represent the relationship between and V?

C D A B C D 44 According to the Bohr model of the hydrogen atom, A the angular momentum of electrons in stable orbits is the same for all energy

levels. B when the quantum number of the electron orbit increases, the angular

momentum decreases. C the angular momentum in an excited state is higher than in the ground state. D the angular momentum for the first three quantum levels are in the ratio of 1 : 1/4 : 1/9

V

1

V

1

V

1

V

1


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45 The minimum wavelength for the continuous X-ray spectrum obtained from an X-ray tube depends on

A the mass of the target. B the electric potential across the anode and cathode. C the element of the target. D surface area of the target. 46 Which of the following is necessary for stimulated emission to occur in the production

of laser? A Population Inversion. B Light of high intensity. C Electron deceleration. D High potential difference. 47 The binding energy per nucleon may be used as a measure of the stability of a

nucleus. This quantity A falls to zero for heavy radioactive nuclides. B increases uniformly throughout the periodic table. C is a maximum for nuclides in the middle of the periodic table. D is directly proportional to the neutron / proton ratio of the nuclide. 48 At a particular instant, the count rate of a pure radioactive material detected by a

detector is 208 s-1 . Four minutes later, the count rate recorded decreases and becomes 40 s-1 . The average background count rate in the absence of the radioactive material is constant at 16 s-1. What is the half-life of the radioactive material?

A 30 s B 40 s C 60 s D 80 s

49 The energy in the sun is obtained through the process of A liberation of energy from unstable nucleus. B nuclear fission of helium nucleus to from hydrogen nucleus. C the fission of uranium nucleus by neutrons. D the fusion of hydrogen nucleus to form helium nucleus. 50 A quark A has no mass. B is positively charged. C has fractional charge. D travels at the speed of light


- 1 -

NAMA :. Tingkatan :

SULIT

960/2

SEPTEMBER 2008

PEPERIKSAAN PERCUBAAN

SIJIL TINGGI PELAJARAN MALAYSIA

NEGERI PAHANG DARUL MAKMUR

PHYSICS

PAPER 2

Two and a half hours

Instructions to candidates:

Answer all the questions in Section A in the spaces provided. All working

must be shown. For calculations, relevant values of constants in the Data Booklet

must be used. For numerical answers, units must be quoted wherever they are

appropriate.

Answer any four questions from Section B. For this section, write your

answers on the answer sheets provided. Begin each answer on a fresh sheet of

paper, and arrange your answers in numerical order. Tie your answer sheets to

this booklet. Answers may be written in either English or Malay. A Data Booklet is provided.

Arahan kepada calon:

Jawab semua, soalan dalam Bahagian A dalam ruang yang disediakan.

Semua kerja mestilah ditunjukkan. Bagi penghitungan, nilai pemalar yang

berkaitan dalam Buku Data mestilah digunakan. Bagijawapan berangka, unit

mestilah dinyatakan di mana-mana yang sesuai.

Jawab mana-mana empat soalan daripada Bahagian B. Untuk bahagian ini,

tulis jawapan anda pada helaian jawapan yang dibekalkan. Mulakan setiap

jawapan pada helaian kertas yang baru, dan susunjawapan anda mengikut tertib

berangka. Ikat helaian jawapan anda bersama dengan buku soalan ini. Jawapan boleh ditulis dalam bahasa Inggeris atau bahasa Melayu. Buku Data dibekalkan.

For examiner's use (Untuk kegunaan

pemeriksa)

1

2

3

4

5

6

7

8

9

10

11

12

13

14

Total

(Jumlah)


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Section A [40 marks]

Answer all questions in this section 1 Fig. 1(a) shows a woman lifting a bowling ball of weight 60 N. Fig. 1 (b) represents a

mechanical model of the backbone of the woman where B represents her pivot point, Tm is the tension in her back muscle , the force 60N represents the weight of the bowling ball and the force 250 N represents the weight of her upper part of her body. The force H and V are the horizontal and vertical components of the reaction force at the pivot point respectively.

Figure 1

(a) Find the tension, Tm in her back muscle. [2 marks]

(b) Determine the force H and V act in her spine when her back is horizontal. [3 marks]

A

B


- 3 -

2 A uniform copper rod with thermal conductivity 380 W m-1 K-1 which is perfectly insulated has a cross-sectional area of 2.50 cm2 and length 20.0 cm. Heat is conducted by the copper rod. When the steady state is achieved, the temperatures at the ends of the rod are 130 oC and 20 oC.

Calculate

(a) the rate of heat flow in the rod. [3 marks] (b) the temperature 15.0 cm from the hot end. [2 marks]

20 oC 130 oC

insulation Copper rod

Figure 2


- 4 -

3 Suppose a tunnel could be dug through the Earth from one side to the other along a diameter as shown in Fig. 3. The average density of the Earth is given

as .

(a) Figure 3 shows that the motion of a particle m dropped into the tunnel is simple harmonic motion where

= 3

4 G , where G is the universal gravitational constant.

[3 marks]

(b) If the average density of the Earth, = 5.51 x 103 kg m-3, what is the period of the particle? [2 marks]

m

Earth

Tunnel

Figure 3


- 5 -

4 An open pipe has a fundamental frequency of 300 Hz. The first overtone of a closed pipe has the same frequency as the first overtone of the open pipe. If the speed of sound in air is 343 m s-1,

(a) What is the length of the open pipe. [2 marks]

(b) What is the length of the closed pipe ? [3 marks]


- 6 -

5 (a) State Coulombs Law [1 mark] ... (b)

Figure 4 shows two point charges +Q and -4Q placed in a box at a distance l from each other. Describe the nature of the resultant force on a point charge +Q [ attractive (attracted by the box) , repulsive ( repulsed by the box) , experience no force at all ] when it is placed at [4 marks]

(i) various positions along PS

(ii) various positions along AD

+Q -4Q A B C D P Q R S

l l l l

Figure 4

l

Box


- 7 -

6

(a) Figure 5a shows a wire PQ travelling at constant speed in the region ABCD of uniform magnetic field. There is no magnetic field outside the region ABCD.

(i) Draw on the diagram the direction of the induced current. [1 mark]

(ii) On the diagram, label the polarity P and Q . [1 mark]

(iii) Describe what happens to the galvanometer. [1 mark]

A

B C

D

P

Q

G

Galvanometer

Direction of motion

Figure 5a


- 8 -

(b)

Figure 5b shows two wires PQ and RS moving at constant speed in the region ABCD of uniform magnetic field. P and R are connected with connecting wires. Describe what happens to the galvanometer. Explain your answer. [2 marks]

A

B C

D

P

Q

G

R

S

Figure 5b

Direction of motion


- 9 -

7 (a) Lasers are highly unidirectional and can have very high intensity. What are the other two characteristics of lasers. [1 mark] (b) Explain how these two characteristics are produced in a laser. [2 marks] (c) Hence explain the meaning of light amplification which is required to produce light of high intensity. [1 mark] (d) For light amplification to occur there must be more atoms in the excited state than in the ground state. Name this situation. [1 mark]


- 10 -

8 (a) Name the four basic forces of nature and their respective ranges. [2 marks] ... (b) Elementary particles are classified into leptons and hadrons according to the basic forces. Hence explain the difference between leptons and hadrons. [1 mark] (c) Hadrons are made up of smaller constituents called quarks. The proton and neutron are examples of hadrons. State the type of quarks that made up the proton and the neutron. Hence explain why the proton has a charge of +e but the neutron has no charge at all. [2 marks]


- 11 -

Section B [60 marks]

Answer any four questions in this section 9 (a) (i) State the principle of conservation of linear momentum. [2 marks] (ii) Distinguish between an elastic collision and an inelastic collision. Give an example of each type of collision. [4 marks] (b) A bullet of mass 0.020 g is fired from a gun of mass 3.0 kg. The velocity of the bullet is 300 ms-1 . Calculate the velocity of recoil of the gun. [3 marks] (c) The bullet travels horizontally and then embeds itself in the centre of a stationary block of wood of mass 1 kg which is suspended by a light vertical string , causing the wood to swing to a certain height. (i) Describe the energy changes that takes place. [1 mark ] (ii) Calculate the initial velocity of the block of wood after collision with the bullet.

[2 marks] (iii) Calculate the vertical height through which the wood has been raised.

[3 marks] 10 (a) A body of mass m moves with constant speed v in a circle of radius r.

(i) Write down an expression for the force necessary to maintain the motion. [1 mark] (ii) What is the direction of the force and what is it called ? [2 marks] Figure 6 shows a roller coaster track which consists of a vertical loop of radius 10 m . A carriage is released from rest at position X. The carriage moves down the track , goes round the vertical loop , and moves in the direction of Z (b) Assuming the track is frictionless , explain the energy changes of the carriage as it moves from X to Z. [5 marks] (c) If the carriage is to complete a circular motion in the loop , determine (i) the force(s) that provide the centripetal force at the highest position P. [1 mark] (ii) the minimum speed that must be achieved at the highest position P. [3 mark]

(d) What is the minimum height h which gives the minimum speed calculated in (c) (ii) above ? [3 marks]

X

ZY

P

hFigure 6


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11 (a) (i) What is meant by the degree of freedom of a gas molecule ? [1 mark] (ii) Explain why the number of the degrees of freedom of a diatomic gas molecule is different at temperatures 30 K , 300 K and 3000 K. [3 marks] (b) (i) State the law of equipartition of energy. [2 marks] (ii) A molecule of an ideal gas has f degrees of freedom. By using the law of equipartition of energy , deduce an expression for internal energy U of n moles of the ideal gas. [2 marks] (iii) If the pressure of the ideal gas is p , and its volume is V , deduce an expression for internal energy U of the gas in terms of f , p and V. [2 marks] (c) A container of volume 2.0 x 10-3 m3 contains 8.0 g of helium gas at pressure 1.01 x 105 Pa. (i) What is the degree of freedom of helium gas molecule? [1 mark] (ii) What is the internal energy of the gas ? [2 marks] (iii) What is the mean kinetic energy of one molecule of helium gas ? [2 marks] 12 (a) (i) State Faradays law of electromagnetic induction. [1 mark ] (ii) Write an equation that shows Faradays law and Lenzs law. Explain why Lenzs law is in accordance with the law of conservation of energy. [2 marks] (b) A small coil is positioned so that its axis lies along a large magnet as shown in figure 7

The coil has a cross-sectional area of 0.4 cm2 and contains 150 turns. The average magnetic flux density B through the coil varies with distance x between the face of the magnet and the plane of the coil as shown in the graph.

Figure 7


- 13 -

(i) The coil is 5.0 cm from the face of the magnet.Use the graph in Figure 8 to determine the magnetic flux density in the coil. [2 marks]

(ii) Hence show that the magnetic flux linkage of the coil is 3.0 x 10-4 Wb. [2 marks]

(iii) The coil is moved along the axis of the magnet so that the distance x changes from x =5.0 cm to x =15.0 cm in a time of 0.30 s. Calculate the average e.m.f. induced in the coil. [4 marks]

(iv) State and explain the variation, if any , of the speed of the coil so that the induced e.m.f. remains constant during the movement. [2 marks]

(v) If the e.m.f. induced is connected in series with a resistor of resistance 2 , what is the current in the circuit ? [2 marks]

Figure 8


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13 (a) An electron is accelerated through a voltage of 260 kV in vacuum .

(i) Calculate the final velocity of the electron. [2 marks]

(ii) Explain why this is impossible to achieve in experiment. [1 mark]

(b) In an x-ray tube, an electron is accelerated by a voltage of 50 kV. The electron is stopped by a heavy metal target in a single collision. Calculate the wavelength of this x-ray photon. [3 marks] (c) A monochromatic x-ray beam was directed at a crystal. Intense reflected beams of

this incident x-ray beam were found at glancing angles of 24.60 and 56.40. No other strong reflection was found. If the wavelength of the x-rays is 1.30 x 10-10 m, calculate the distance between the layers of atom in the crystals which caused this diffraction. [3 marks]

(d) An x-ray tube has a tungsten target. The energy of an electron in the various shells of the tungsten atom is K - shell - 1.50 x 10-15 J L - shell - 0.24 x 10-15 J M shell - 0.12 x 10-15 J (i) What is the minimum potential difference across the tube for it to emit x-ray

line spectrum in the K series ? [3 marks] (ii) What is the wavelength of the K line ? [3 marks]

14 (a) (i) Explain what you to understand by the terms mass defect and binding energy per nucleon. [3 marks] (ii) Calculate the binding energy per nucleon of oxygen in MeV. ( mass of 168 = 15.995 u , m p = 1.0078 u and m n = 1.0087 u ) [ 3 marks]

(b) K - 40 is a radioisotope of potassium with half-life 1.38 x 109 years. It decays into Ar-40. In a particular sample of rock, the ratio of potassium atoms to Ar -40 atoms is 1: 31. Estimate the age of the rock. [3 marks]

(c) (i) In thermonuclear fusion, the temperature is 108 K. Explain why such a high temperature is required. [2 marks]

(ii) Identify the particles P, Q and R in the following equations of thermonuclear fusion. 21 H +

21 H

32 He + P + 3.25 MeV

31 H +

21 H

42 He + Q + 17.6 MeV

4 11 H

42 He + 2

0+1 R + 2 S + 27 MeV

[3 marks] S has practically no mass and travels with the speed of light. Name another important property of S. [1 mark]


SKEMA PEMARKAHAN

PEPERIKSAAN PERCUBAAN STPM 2008

PHYSICS PAPER 1

1 A 6 A 11 B 16 D 21 D

2 C 7 C 12 A 17 B 22 D

3 B 8 D 13 D 18 A 23 C

4 A 9 A 14 A 19 B 24 D

5 C 10 B 15 C 20 C 25 B

26 D 31 A 36 A 41 C 46 A

27 C 32 D 37 B 42 D 47 C

28 B 33 B 38 A 43 A 48 D

29 C 34 C 39 B 44 C 49 D

30 D 35 B 40 B 45 B 50 C


SKEMA PEMARKAHAN PHYSICS TINGKATAN 6 ATAS TRIAL PAPER 2

SECTION A

1 Consider a woman lifting a 60 N bowling ball as shown in Fig. 1(a). Find the tension, Tm in her back muscle. Also, determine the force H and V act in her spine when her back is horizontal. Approximate the situation as shown in Fig. 1(b) and assume the upper part of her body to weigh 250 N with centre of gravity as indicated.

Figure 1 (a) Taking moment at the pivot,

Tm sin 12o ( L

3

2) = 60 (L) + 250 (

2

L).(1)

Tm = 1335 N ..(1) [2] (b) Consider vertical component, Tm sin 12

o + V = 60 + 250..(1) 1335 x sin 12o + V = 310 V = 32.4 N.(1) Consider horizontal component, Tm cos12

o = H H = 1335 x cos 12o

H = 1306 N..(1) [3]


2 A uniform copper rod with thermal conductivity 380 W m-1 K-1 which is perfectly insulated has a cross-sectional area of 2.50 cm2 and length 20.0 cm. Heat is conducted by the copper rod. When the steady state is achieved, the temperatures at the ends of the rod are 130 oC and 20 oC. Calculate (a) the rate of heat flow in the rod.

dx

dkA

dt

dQ = ..(1)

= (380) (2.5 x 10-4) (21020

20130

x) .(1)

= 52.25 W ..(1)

[3] (b) the temperature 15.0 cm from the hot end.

The temperature at 15.0 cm = (15 x 10-2) ( 21020

20130

x)

= 82.5 oC ....(1) The temperature 15.0 cm from the hot end = 130 oC 82.5 oC = 47.5 oC .(1) [2]


3 Suppose a tunnel could be dug through the Earth from one side to the other

along a diameter as shown in Fig. 3. The average density of the Earth is given as . (a) Show that the motion of a particle m dropped into the tunnel is simple harmonic

motion where = 3

4 G.

By using the Newtons second law of motion, F = ma

2

'

r

mGM = ma ..(1)

)3

4( 3

2r

r

G = a where 3

3

4' rM = (1)

a = rG

)3

4(

a = - 2 r

where = 3

4 G (1)

[3]

(b) If the average density of the Earth, = 5.51 x 103 kg m-3, what is the period of the particle?

T =

2..(1)

T =

G4

32

T = )1051.5)(1067.6(4

32

311xx

T = 5064 s / 84.4 min ..(1) [2]

m

Earth

Tunnel


4. An open pipe has a fundamental frequency of 300 Hz. The first overtone of a closed pipe has the same frequency as the first overtone of the open pipe. How long is each pipe? [Speed of sound in air = 343 m s-1] (a) For open pipe,

Fundamental frequency, fo = x

v

2 ( x =

2

)

x = 3002

343

x

x = 0.5717 m ..(1)

First overtone, f1 = x

v ( x = ) ..(1)

(b) For closed pipe,

First overtone, f1 = y

v

4

3 ( y =

4

3) .(1)

x

v =

y

v

4

3

y = 4

5717.03x (1)

y = 0.4288 m .(1)

[5]


5. (a) State Coulombs Law

The force F between two point charges is directly proportional to the product of the

charges and inversely proportional to the square of the distance between the charges.

Or

2

21,r

QQFForce where Q1, Q2 are the point charges

r is the distance between the two charges

OR

2

21,r

QQkFForce = where Q1, Q2 are the point charges


k is the constant of proportionality

OR

2

0

21

4,

r

QQFForce

= where Q1, Q2 are the point charges


0 is the permittivity of free space for charges in free space

[1]

(b)

The diagram above shows two point charges +Q and -4Q placed in a box at a distance l

from each other.

Describe the nature of the resultant force on a point charge +Q when it is placed at

[ attractive (attracted by the box) , repulsive ( repulsed by the box) , experience no force

at all ]

(i) various positions along PS

+Q -4Q A B C D P Q R S

l l l l l

Box


Attractive / Attracted by the box [1]

(ii) various positions along AD

Along AC = Attractive / Attracted by the box / Force to the right [1]

At the point C = No force / Equilibrium / No nett force / Zero [1]

Along CD = Repulsive force / Repulsed by the box / Force to the left [1]

6.

The diagram above shows a wire PQ travelling at constant speed in the region ABCD of

uniform magnetic field. There is no magnetic field outside the region ABCD.

(i) Draw on the diagram the direction of the induced current. [1]

(ii) Label the polarity P and Q . [1]

(iii) Describe what happens to the galvanometer.

The galvanometer pointer moves / deflects in one direction. [1]

[3]

A

B C

D

P

Q

G

+

-

Galvanometer


The diagram above shows two wires PQ and RS moving at constant speed in the region

ABCD of uniform magnetic field. P and R are connected with connecting wires.

Describe what happens to the galvanometer. Explain your answer.

The galvanometer does not moves.

Because there is no current moving through the galvanometer. [1]

The polarity / potential of Q and S is the same. [1]

[2]

A

B C

D

P

Q

G

R

S


7. (a) Lasers are highly unidirectional and can have very high intensity. What are the

other two characteristic of lasers.

Monochromatic

Coherent

[1]

(b) Explain how these two characteristic are produced in a laser.

When an atom is in an excited state, and there exist a passing photon of frequency f, this

passing photon will stimulate the excited atom to move to the ground state and emits a

photon of frequency f also. (1)

This process is called stimulated emission.

The emitted photon and the external photon have the same frequency and in phase.

Hence they are monochromatic and coherent. (1)

[2]

(c) Hence explain the meaning of light amplification which is required to produce light of

high intensity.

When the process of stimulated emission occurs for a while, a large number of photons

of the same wavelength, in phase , plane polarised and moving in the same direction are

produced. Superposition of these light waves produces light of high intensity.

[1]

(d) For light amplification to occur there must me more atoms in the excited state than in

the ground state. Name this situation.

Population inversion

8. (a) Name the four basic forces of nature and their respective ranges.

Name of Forces Range

Gravitational Force Long

Electromagnetic Force Long

Strong Nuclear Force Short

Weak Nuclear Force Short

Every 2 ticks = 1 mark [2]

(b) Elementary particles are classified into leptons and hadrons according to the basic

forces. Hence explain the difference between leptons and hadrons.

Leptons experience only gravitational, electromagnetic and weak nuclear force /

Leptons experience only 3 of the 4 forces of nature except the strong nuclear force.

Hadrons experience all four forces of nature.

[1]


(c) Hadrons are made up of smaller constituents called quarks. The proton and neutron

are examples of hadrons.

State the type of quarks that made up the proton and the neutron. Hence explain why the

proton has a charge of +e but the neutron has no charge at all.

Proton is made up of 2 up quarks and 1 down quark.

Neutron is made up of 2 down quarks and 1 up quark. (1)

Up quark has a charge of +3

2e

Down quark has a charge of -3

1e

Charge of proton = +3

2e +

3

2e -

3

1e = +e

Charge of neutron = -3

1e + (-

3

1e) +

3

2e = 0 (neutral) (1)

[2]


SECTION B

Answers 9 (a)(i) (ii) (b) (c) (i) (ii) (iii)

Total linear momentum of a system of bodies is constant, if no external forces act on the system

Elastic collision Inelastic collision Kinetic energy is conserved Kinetic energy is not

conserved Relative speed of approach = relative speed of separation

Relative speed of approach > relative speed of separation

Coefficient of restitution = 1 Coefficient of restitution = 0 Example : Collision of two billiard balls

Example : Collision of two cars

Total momentum is conserved 0 = (0.02 x 300) + 3v v = -2ms-1 Kinetic energy to potential energy (0.02 x 300) + 0 = (0.02 + 1)v V = 5.88 ms-1

Loss in kinetic energy = gain in potential energy x 5.88 2 = 9.81 x h h = 1.76 m

2

2 (any 2)

2

3

1

2

3

10 (a) (i) (ii) (b) (c) (i) (ii)

F = or F = m2 r Towards the centre of the circle. Centripetal force At X, PE maximum X to Y, PE decreases , KE increases At Y , PE = 0 , KE is maximum Y to P , KE decreases , PE increases P to Y, PE decreases , KE increases Y to Z , KE constant Weight of carriage and normal reaction, R Track frictionless, R = 0

1

2

1

1

1

1

1

1

mv2 r


(d)

vp = 10 x 9.81 = 9.90 ms-1 At P , total energy = PE + KE 9.81 x h = x 9.92 + (9.81 x 20) h = 25 m Answers

3

1

2

11 (a) (I) (ii) (b) (i) (ii) (iii) (c) (i) (ii) (iii)

The number of independent ways by which energy is absorbed by the gas molecules. 30 K - f = 3 translational KE only 300 K - f = 5 translational 3, rotational 2 3000 K - f = 6 translational 3, rotational 2 , vibrational 1 Energy supplied to a system is distributed equally among all the f , each f has energy E = 1/2kT KE mean of 1 molecule = f/2 kT KE mean of 1 mole = f/2 RT U for 1 mole = f/2 nRT pV = nRT U = f/2 nRT = f/2 pV Helium is monatomic , f = 3 U = f/2 pV = 3/2 x 1.01 x 105 x 2 x 10-2 = 303 J U = n KE mean KE mean of 1 molecule =

= = 2.52 x 10-22 J

1 3 2 2 2 1 2 2

U 2 x NA

303

2 x 6.02 x 1023


12 (a) (i) When the magnetic flux linked with a circuit changes, an

electromotive force which is directly proportional to the rate of change of magnetic flux is induced

[1]

(ii) Induced e.m.f. = - d / dt

When an e.m.f. is induced, the electrical energy generated is from the conversion of mechanical work done in opposing the force produced by the effect of the induced current.

[1] [1]

(b) (i) 50 mT

[1] [1]

(ii) flux linkage = BAN = 50x10-3x0.4x10-4x150 = 3.0 x 10-4 Wb

[1] [1]

(iii) new flux linkage = 8.0x10-3x0.4x10-4x150=4.8x10-5 Wb

Change = 2.52 x10-4 Wb e.m.f. = 2.52x10-4/0.3 =8.4 x10-4 V (iv) for a small change in distance x (change in) flux linkage decreases as distance increases so speed must increase to keep rate of change constant (v) I = V/R = 8.4 x10-4 / 2 = 0.42 mA

[1] [1] [1] [1] [1] [1] [1] [1]

13 (a) (i) mv2 = eV v = ( 2x 1.6 x10-19x260x103 /9.11-31) = 3.02 x 108 m s-1

(ii) No particle can travel faster than the speed of light.

(b) min = eV/ hc = 1.6 x10-19x50x103 / 6.63x10-34x3x108

= 4.02 x10-10 m (c) 2 d sin = n n= 2 , = 56.40

d = 1.30 x10-10 / sin 56.40 = 1.56 x 10-10 m (d) (i) eV = 1.5 x 10-15 V = 1.50 x 10-15 / 1.6 x 10-19 = 9.38 kV

[1] [1] [1] [1] [1] [1] [1] [1] [1] [1] [1] [1]


(ii) = hc/ E = 6.63 x10-34 x 3.0x108/ (-0.24x10-15+ 1.50x10-15) = 1.58 x 10-10 m

[1] [1] [1]

14.

(a)(i) The difference between the total mass of the nucleons and the mass of the nucleus. The binding energy of a nucleus is the energy required to separate completely all the nucleons in the nucleus. Binding energy per nucleon = Binding energy of nucleus/no. of nucleons. (ii) Mass defect = [8 ( 1.0078 + 1.0087 ) -15.995] x 1.66 x 10-27 = 2.27 x 10-28 kg

Binding energy per nucleon = 2.27 x 10 -28 x 9 x 1016 / 16 x1.6x10-13 = 7.98 MeV

(b) no.of K atoms/no.of Ar atoms = 1/31 no.of K atoms / total no. of K and Ar atoms = 1/ 1+ 31 =1/32 Time taken = 5 half- lifes Age of the rock = 5X 1.38 x109 = 6.90 x 109 years. (c) (i) To over come the high repulsive force of the deuterium

nuclei, the kinetic energy must be very high. To achieve this high kinetic energy, the temperature must be raised to about 108 K

(ii) P is neutron Q is neutron R is positron S does not interact with matter. It can travel vast distance in matter without experiencing any collision.

[1] [1] [1] [1] [1] [1] [1] [1] [1] [1] [1] [1] [1] [1] [1]

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