Chapter 1

Introduction to Physics

Cikgu Desikan

Edited by

SMK Changkat Beruas, Perak

Cikgu Khairul AnuarIn collaboration with

SMK Seri Mahkota, Kuantan

PHYSICSFORM 4

FO

RM

4 P

HY

SIC

S

2016

1. Understanding Physics

2. Understanding base quantities and derived quantities

3. Understanding scalar and vector Quantities

4. Understanding measurements

5. Analysing scientific investigations

Analysis of Past Year Questions

Learning Objectives :

Dear students,

With the new day comes new strength and new

thoughts.

Introduction to Physics

Chapter 1

2007 2008 2009 2010 2011 2012 2013 2014 2015

P1 3 3 3 2 3 3 4 1

P2

A - - - 1 - 1 - -

B - - - - - - - -

C - - - - - - - -

P3A - 1 1 1 - - 1 -

B - - - - - - - -

Concept Map

Dear students,

By failing to prepare, you are preparing to fail !!!

Introduction to Physics

Physics

ConceptsPhysics Quantity Measurement Scientific

Investigation

Field of

Physics

Base

Quantity

Approximation

Introduction to Physics

Derived

Quantity

Base Unit Derived Unit

Prefix Scientific

Notation

Conversion of

Units

Instrument for

Measurement

Error

Accuracy

Sensitivity Consistency

Chapter 1

1.1 Understanding Physics

What is Physics?

Fields of study

in physics

1.__________ & ________

Investigate the action of

force and motion

2. _________________

Studies the influence of

heat on different

types of matter 3. ________________

Explains the different

phenomena due to light

4. _________________

Understand the

properties of different

types of waves and

their uses

6. ___________

Studies the use of

electronic devices in

various fields

5. _______________

Investigates the

interactions of electric &

magnetic fields

7. ______________

Study of nuclear

structure and their

application

4

Derived quantities

(symbol)Expressed in base quantities Derived units

Area, A

Volume, V

1.2 Physical Quantities

Physical Quantities is a physical

characteristic that can be measured.

All physical quantities can be classified

into two groups :

1. ____________________________

2. ____________________________

Base quantities

Base quantities are quantities that cannot be

___________ in terms of other base quantities.

Base quantity Symbol S.I. Unit

Symbol

for S.I.

Unit

Length

Mass

Time

Current

Temperature

Derived quantity is one which obtained by

__________________ base quantities by

multiplication, division or both these

operations. Its unit is derived from a

similar combination of the base units.

1

2

5

Derived quantities

6

Derived

quantities

(symbol)

Expressed in base quantities Derived units

Density , ρ

Velocity , v

Acceleration, a

Momentum, p

Force, F

Pressure, P

Weight, W

Scientific form

Write the following quantities in standard

form :

The values of measurements which is either

very large of very small are written in

Standard Form so as to be neater, brief and

easier to read.

A x 10n ,

1 < A < 10 and n = integerPrefix Value

Standard

formSymbol

Tera1,000,000,000,

000

Giga 1,000,000,000

Mega 1,000,000

Kilo 1,000

Hecto 100

Deca 10

Deci 0.1

Centi 0.01

Mili 0.001

Micro 0.000 001

Nano 0.000 000 001

Pico0.000 000 000

001

Prefix is used to simplify the expression of very

big or very small numerical values of physical

quantities

7

a. Radius of the earth = 6 370 000 m

b. Mass of an electron

= 0.000 000 000 000 000 911 kg

c. Size of a particle = 0.000 03 m

d. Diameter of an atom = 0.000 000 072 m

e. Wavelength of light = 0.000 000 55 m

Prefixes

Convert each of the following measurements

into metre, m

(a) 2.98 Tm

(b) 298 km

(c) 2.98 μm

(d) 2.98 x 10-1 Gm

(e) 2.98 x 10-3 Mm

(f) 29.8 x 107 nm

(g) 298 x 104 μm

8

Conversion of Units

Exercise 3.1

9

Convert

a. 4 m2 into the units of cm2

b. 30 cm2 into the units of m2

c. 2.5 m2 to unit of mm2

d. 500 mm2 into the units of m2

e. 200 m3 into the units of mm3

f. 11.5 cm3 into the units of m3

g. 72 km h-1 into the units of ms-1

h. 5 g cm-3 into the units of kg m-3

1.3 Scalar and Vector Quantities

Distance(s) Displacement(s)

Total of the path traveledDistance between two points measured along a

specific _________________

quantity quantity

Speed Velocity

Rate of ______________of distance Rate of ______________ of displacement

Speed = Velocity =

quantity ____________ quantity

10

Scalar Quantities Vector Quantities

Examples

Consistency Accuracy Sensitivity

Shooter Consistency Accuracy

A

B

C

D

The diagram shows the result for four shooters A, B, C and D

in a tournament. Every shooter shot five times.

(Use High / Low)

11

1.4 Measuring Instruments

Consistency in

measurements refers to how

little deviation there is

among the measurements

made when a quantity is

measured several times.

Accuracy of a measurement

is how close the

measurement made is to the

actual value of the quantity.

Sensitivity of an instrument is

its ability to detect a small

change in the quantity to be

measured in a short period

of time.

ERROR

Error is _______________caused by measuring instrument or the observer or the physical

factors of the surroundings.

Systematic Error Random Error

Caused by:

i. Condition of the measuring instrument

ii. Condition of environment

Caused by:

i. Surroundings factors, such as

temperature and wind

ii. Carelessness of the observer

Example

i. ______________________________

ii. Inaccurate calibration

Example

i. Parallax error ii. Error in counting

iii. Natural errors (sudden change)

Way of correction

i. Proper calibration

ii. Adjust the instrument frequently

Ways of correction

i. Take several readings and calculate

the average value.

A parallax error is an error in reading an instrument because the observer’s eyes and pointer are

not in line / perpendicular to the plane of the scale.

1. position of eyes must be in line/ perpendicular / 90o with the scale of the reading to be taken.

2. When taking reading from an ammeter, we must make sure that the eyes are exactly in front of

the pointer, so that the reflection of the pointer in the mirror is right behind the pointer. In other

words, the reflection of the pointer on the mirror could not be seen by the observer, then it is

free from parallax error.

How to avoid parallax error?

12

Parallax Error

Measuring Instruments & Accuracy

Physical Quantity Measuring Instrument

Length

Current

Mass

Temperature

Time

Voltage

13Parallax Error

A

B

C

1 2 3

Accurate reading = 2.6 cm

Reading = 2.7 cm

Reading = 2.6 cm

Reading = 2.5 cm

B

A

C

Reading = 15.0 ml

Reading = 15.1 ml

Reading = 14.9 ml

15

16

14

Pointer’s image can be seen Pointer’s image is behind the pointer

Depth probe

Measure

depths

Outside jaws

Measure external diameter

of an objectVernier

scale

(in)

Retainer

Block

movable

parts

Vernier

scale

(cm)

Main scale

(cm)

Main scale

(in)

Inside

jaws

Measure

internal

diameter/

thickness

of an object

VERNIER CALLIPER

Measurements

Reading from main scale :

Reading from main Vernier scale :

Reading of Vernier caliper : 14

Tiada Ralat Sifar

15

10

0 5 10

Ralat Sifar Negatif Ralat Sifar Positif

Senggatan keenam pada Skala Vernier

segaris dengan senggatan pada Skala Utama

Ralat Sifar Positif

=

10

0 5 10

Skala Utama

Skala Vernier

Senggatan keenam pada Skala Vernier

segaris dengan senggatan pada Skala Utama

Ralat Sifar Negatif

=

Skala Utama

Skala Vernier

Skala Utama

Skala Vernier

cm

0

0

5 10

1

16

1. Write down the readings shown by vernier calipers in the following figures:

0 1

0 105

b)0 1

0 105

a)

Try this !!!

0 1

0 105

d)0 1

0 105

c)

Reading of the main scale

=

Reading of the thimble scale

=

Diameter of ball bearing

=

17

MICROMETER SCREW GAUGE

The object which to be

measured is placed

between the jaws (spindle).

The thimble is

turned until its jaw

touches the object.

The ratchet knob

prevents

overtightening by

making a click

sound when the

micrometer is ready

to be read.

main scale

Vernier

scaleHorizontal

reference

line

00

5

40

45

0

05

40

10

45

No Zero Error

18

To elliminate the zero error ***

Correct Reading =

Horizontal

reference

line

0 mark

0

05

10

45

Horizontal

reference

line

2nd mark

above 0

Horizontal

reference

line

3th mark

below 0

Positive zero error = Negative zero error =

0 105

2 3c)

0 105

3 4a)

0 105

1 2d)

0 105

6 7b)

Exercise 3.4

2. Write down the readings shown by the following micrometer screw gauges.

a) b)

19

0

20

15

25 0 5

15

20

1. Write down the readings shown Vernier calipers in the following figures:

20

3. The following diagram shows the scale of a vernier callipers when the jaws are closed.

The following diagram shows the scale of the same vernier callipers when there are 50

pieces of cardboard between the jaws. Determine the thickness of one piece of cardboard.

0 1

0 105

5 6

0 105

(a) (b)

20 30

21

Metre Rule

A V

Ammeter Voltmeter

Thermometer

Mercury

BulbMercury column

Sensitivity & Accuracy of Measuring Instruments

Digital Stopwatch

Instrument Sensitivity Accuracy

Metre Rule

Vernier Calliper

Micrometer Screw Gauge

Ammeter (0 – 5 A)

Miliammeter (0 – 50 mA)

Thermometer (-10 ºC – 110 ºC)

Mechanical stopwatch

Digital stopwatch

22

Miliammeter

Mechanical

Stopwatch

1.5 Scientific Investigation

______________________________

The quantity whose values we deliberately

choose to change or a primary variable which

causes other secondary variable to change.

________________________________

The quantity whose value depend on the

manipulated variable or a secondary variable

which changes in response to the change in

the manipulated variable.

________________________________

The quantity whose value is kept constant

throughout the experiment.

23

Identifying the problems/ questions /

situations

Identifying the variables involve

Forming a Hypothesis

Recording and Presenting data

Design and Carry out an experiment

Analysing and Interpreting data

Making conclusion

Writing a Report

The problem is identified and stated by asking

question. The problem is usually arised from

an observation

The question asked must be one that can be

solved experimentally.

2

1

Identifying the variables involve

Manipulated variable

Identifying the problems/ questions /

situations

Responding variable

Constant variable

A general statement about the relationship

between a manipulated variable and a

responding variable.

The hypothesis should be written as :

The greater the………, the greater the…….

or

The bigger the…………, the smaller the…..

3 4

24

Aim

A statement to show the investigation of

the variables involve. The aim of the

experiment should be written as:

To investigate the relationship between

………..and ………………

Apparatus

List the apparatus and materials used so

that at least a set of data for manipulated

and responding variables can be

determined. State the arrangement of the

apparatus that can function by drawing a

labeling diagram.

Procedure

1. State the method of controlling the

manipulated variables

2. State the method of measuring the

responding variables

3. Repeat the experiments at least four

times.

When the data is organised in a table, it is

easier to analyse than recorded

randomly.

5

6

7

8

25

Plot a graph of ( Responding variable)

against (Manipulated variable)

How to analyze the data ?

(a) Determine the relationship between

two variables.

(b) Determine the gradient of the graph

Based on the analysis and data

interpretation, make a rational conclusion

Report must be written after the scientific

investigation is completed.

The report must consist of aim, problem

statement, hypothesis, variables,

apparatus and material, procedure,

result, discussion and conclusion.

x

y

0x

y

0

F

a

a ∝ F

m

a

1

m

a

0 0 0

a ∝ 1

ma ∝1

m

Relationship between two variables

26

2. Which of the following is the best graph ?

The equation of the graph above is

A) P = 10Q + 5 B) P = 2Q + 10

C) P = – 2Q + 10 D) P = 5Q – 10

1. Which of the following force-compression

graphs shows that the compression,x of a

spring is directly proportional with the force

that is applied, F?

3.A. B.

x

F

x

F

x

F

x

F

27

C. D.

A. B.

x x

F F

C. D.

x x

F F

Q

P

5

10

Revision Questions

28

4. Table shows the readings of the length of a rod as recorded by two students, X and Y

Reading of student X/cm Reading of student Y/cm

2.42 2.43

2.38 2.41

2.40 2.38

2.36 2.34

a) What was the instrument used by both students?

b) Why four readings were taken for each measurement?

c) What is the average value of the readings made by

i) student X ?

ii) student Y ?

d) Which set of reading is more accurate? Why?

e) Apart from the instrument in (a), what instruments can be used although they are

less accurate?

Load

W/N

Time for 10

oscillations, t/s

Period of

oscillation, T/sT2/s2 W/T2 N s-2

1.0 6.7

2.0 9.5

3.0 11.6

4.0 13.4

The above table shows the experimental data that is obtained by a student using the

weighted spring oscillation system.

a) Name the variable that is manipulated.

b) Name the variable that responds.

c) Complete the above table with the corresponding values.

d) State the derived unit for W/T2.

e) Draw the graph of T2 against W.

f) Interpret the shape of the graph that you have drawn.

g) Calculate the gradient of your graph.

h) Write relationship between the load and the period.

5.

29

10

0.2

30