1.1understanding physics physics - ks thong's blog · jpn pahang physics module form 4...

JPN Pahang Physics Module Form 4Teacher’s Guide Chapter 1 : Introduction To Physics_________________________________________________________________________________________

CHAPTER 1 : INTRODUCTION TO PHYSICS

1.1 Understanding Physics

1

Mechanical Energy

PHYSICS

Study of the natural phenomena and the properties of matter.

Solid

Liquid

Gas

Mechanical Energy

Heat Energy

Light Energy

Wave Energy

Electrical Energy

Nuclear Energy

Chemical Energy

Relationshipwith

matter

Properties of Energy

Relationship with

energy

Properties of Matter

formsstates

Matter Energy

Mechanics

Propertiesof matter

Heat

Light

Wave

in the fields of

Electricity & Electromagnetism

Atomic Physics & Nuclear

Electronics


1.2 PHYSICAL QUANTITIES

Base quantity

1 A physical quantity is ……………………………………………………………………..

2 Examples of scientific instruments:………………………………………………………

3 A base quantity is a physical quantity which cannot be defined in terms of other physical

quantities.

4 Study the following picture and list the physical quantities that can be measured.

5 List of 5 basic physical quantities and their units.

Base quantity Symbol S.I. Unit Symbol for S.I. Unit

Length

Mass

Time

Current

Temperature

6. Two quantities that have also identified as basic quantity. There are:

i) …………………………..unit ………….. ii) ………………………. unit ……………..

The list of physical quantities :

1. ……………………………………….

2. ……………………………………….

3. ……………………………………….

4. ……………………………………….

5. ……………………………………….

6. ……………………………………….

7. ……………………………………….

8. ……………………………………….

9. ……………………………………….

batterybattery

any quantity that can be measured by a scientific instrument.

Stopwatch, metre rule balance, thermometer, ammeter etc.

Height,

mass,

size,

age,

temperature,

current

Power,

Thermal energy

Pressure

l meter m

m kilogram kg

t second s

I Ampere A

T Kelvin K

Light intensity candela Amount of substance mol

2


Standard Form

1 Standard form = A x 10n , 1 < A < 10 and n = integer

2 Standard form is used to …………………………………………………………………...

3 Some physical quantities have extremely small magnitudes. Write the following

quantities in standard form :

a. Radius of the earth = 6 370 000 m =………………………………………………….

b. Mass of an electron = 0.000 000 000 000 000 000 000 000 000 000 911 kg =………...

c. Size of a particle = 0.000 03 m = ………………………………………………………

b. Diameter of an atom = 0.000 000 072 m = …………………………………………...

c. Wavelength of light = 0.000 000 55 m = ……………………………………………..

Prefixes

1. Prefixes are usually used to ………………………………………………………………...

2. It will be written ……………………………………………………………………………

3. The list of prefixes :Tera (T)

Giga (G)

Mega (M)

kilo (k)

mili (m)

micro (µ)

nano (n)

pico (p)

1012

109

106

103

100

10-3

10-6

10-9

10-12

Hekto (ha)Deka (da)

desi (d)centi (c)

102

101

10-1

10-2

Eg :

1 Tm = …………………………………….

3.6 mA = ……………………………………. How to change the unit ;Eg : 1. Mega to nano

2. Tera to micro

3. piko to Mega

simplify the expression of very large and small numbers

6.37 x 106 m

9.11 x 10-31 kg

3.0 x 10-5 m

7.2 x 10-8 m

5.5 x 10-7 m

represent a large physical quantity or extremely small quantity in S.I units.

before the unit as a multiplying factor.

1 × 1012 m

3.6 × 10-3A

1.33 MA = 1.33 × 106 A

= 1.33 × 10 6-(-9) nA

= 1.33 × 10 -15 nA

1.23 Tm to unit µm unit

1.23 Tm = 1.23 x 10 12m

= 1.23 x 10 12 – (-6)m

= 1.23 x 10 18m

5456 pA to MA unit

5456 pA = 5.456 x 10 3 + (-12) pA

= 5.456 x 10 -9pA

= 5.456 x 10 -9 –(6) MA

= 5.456 x 10 -15 MA

3


4. Some physical quantities have extremely large magnitudes. These extremely large and small values can be written in standard form or using standard prefixes. Write the quantities in standard prefixes:a. Frequency of radio wave = 91 000 000 Hz = ………………………………………….

b. Diameter of the earth = 12 800 000 m = ………………………………………………

c. Distance between the moon and the earth = 383 000 000 m = ………………………

d. Mass of the earth = 6 000 000 000 000 000 000 000 000 kg = ………………………

Derived quantities

1 A derived quantity is …….…………………………………………………………………

………………………………………………………………………………………………

2 Determine the derived unit for the following derived quantities.

Derived quantity

Formula Derived unitName of

derived unit

Area area = length x width m x m = m2 –

Volume volume = length x width x height m x m x m = m3 –

Densityvolume

massd =ensity 3

3mkg

m

kg −= –

Velocitytime

ntdisplaceme v =elocity 1sm

s

m −= –

Accelerationtime

velocityinchangeonaccelerati =

2

11-1

sm

ssms

sm

−

−−

=

=–

momentum momentum = mass x velocity kg m s-1 –

Force force = mass x acceleration kg m s-2 Newton (N)

pressurearea

force pressure=

2

2

m

kgms−kg m-1 s-2 (Nm-2) @ Pa

Weight weight = mass x gravitational acceleration kg ms -2 Newton (N)

Work work = force x displacement N m Joule (J)

Powertime

workpower = J s -1

Watt (W)

9.1 × 10 1MHz

12.8 Mm = 1.28 × 10 1 Mm

383 Mm = 3.83 × 10 2 Mm

6.0 × 10 15 Tg

a physical quantity which combines several basic quantities through

multiplication, division or both

4


Derived quantity

Formula Derived unitName of

derived unit

kinetic energy 2velocitymass2

1K.E ××= kg m2s-2 Joule (J)

potential energy

P.E = mass x gravitational acceleration x height kg m2s-2 Joule (J)

charge charge = current x time Ampere second (As)

Coulomb (C)

voltagecharge

workvoltage = J C-1 Volt (V)

resistancecurrent

voltageresistance= VA-1 Ohm (Ω)

Note that the physical quantities such as width, thickness, height, distance, displacement, perimeter, radius and diameter are equivalent to length.

1.3 SCALAR AND VECTOR QUANTITIES

1 Scalar quantities are ………………………………………………………………………

Examples : …………………………………………………………………………………

2 Vector quantities are………………………………………………………………………...

Examples : …………………………………………………………………………………

3 Study the following description of events carefully and then decide which events require

magnitude, direction or both to specify them.

Description of events Magnitude Direction1. The temperature in the room is 25 0C

2. The location of Ayer Hitam is 60 km to the north-west of Johor Bahru

3. The power of the electric bulb is 80 W

4. A car is travelling at 80 km h-1 from Johor Bahru to Kuala Lumpur

1.4 MEASUREMENTS

Quantity which has only magnitude or size

Mass, Length, Speed, volume

Quantity which has magnitude or size and direction.

Velocity, Force, Displacement, Acceleration

√

√ √

√

√ √

5


Using Appropriate Instruments to Measure

1 There are various types of………………………………………………………………….

2 We must know how to choose the appropriate instrument to ……………………………..

3 Examples of instrument and its measuring ability.

Measuring instrument Range of measurement Smallest scale division

Measuring tape

Meter rule

Vernier caliper

Micrometer screw gauge

4 Sample of measuring instruments:

4.1 Ammeter : ……………………………………………………………………………..

4.2 Measuring cylinder : ……………………………………………………....................

4.3 Ruler : ………………………………………………………………………………………

wrong right wrong

10 11 12 13 14 15 Reading = ……………… cm

4.4 Vernier calliper

A venier calliper is used to measure:

a. ………………………………………………b. ………………………………………….

mirror pointer

pointer mirror

Pointer’s image is behind the pointer

incorrect reading correct reading

1 2 30 4

1 2 30 4

Pointer’s image can be seen

Right position of eye (eye are in a line perpendicular to the plane of the scale)

wrong position of eye

wrong position of eye water

is used to determine the volume of liquid.

is used to determine the length

Up to a few meters 0.1 cm

1 m 0.1 cm (0.01 m)

10 cm 0.01 cm

less than 2 cm (20 mm) 0.001 cm (0.01 mm)

is used to measure electric current

measuring instrument with different measuring capabilities.

measure a particular quantity.

small object depth of a hole

external diameter of a cylinder or pipe internal diameter of a pipe or tube

0.1 cm6


c. ………………………………………………d. ………………………………………….

A vernier calliper gives readings to an accuracy of …………………………………...…. cm.

Length of vernier scale = ……… cm

Vernier scale is divided into 10 divisions

Length of the divisions = ………. cm

Example:

The diagram below shows a vernier calliper with reading.

Vernier calliper reading = ……………. cm

4.5 Micrometer screw gauge.

A micrometer screw gauge is used to measure :

a. ………………………………………………

0 5 10

0 1

0 1 2 3 4 5 6 7 8 9 10

0 1 cm

Main scale = ………………….

Vernier scale = …………………..

Final reading = …………………..

Find the division of vernier scale which is coincides with any part of the main scale

0 1

0 5 10

Main scale in cm

Vernier scale

cm 0 1 2 3 4 SKALA

0

inside jawsVernier scale

outside jaws

Main scale

The different between the main scale and vernier scale is = ……………………………. cm

0.9

0.09

0.01 cm

0.2 cm

0.06 cm

0.26 cm

0.15

objects that are small in size

diameter of a wire

diameter of small spheres such as ball bearings

0.5 ÷ 50 0.01 mm 4.50 mm 0.01 mm 0.12 mm 4.62 mm

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b. ………………………………………….

c. ………………………………………………

Example :

4.6 Some others measuring instruments :

……………………… …………………… ……………………… ………..

………………………. …………………….. ………………

Hands-on activity 1.1 on page 1 of the practical book to learn more about choosing

appropriate instruments.

Exercise: Vernier Callipers 1. Write down the readings shown by the following (a)

One complete turn of the thimble(50 division) moves the spindle by 0.50 mm.Division of thimble = ………………….. = …………………..A accuracy of micrometer screw gauge = ……………..

Sleeve scale : ……………

Thimble scale : ………….

Total reading : …………..

Sleeve scale : ……………

Thimble scale : ………….

Total reading : …………...

0 5 10

7 8

2.00 mm

0.22 mm

2.22 mm

Analogue stopwatch digital stopwatch thermometer Ammeter

Measuring tape measuring cylinder beaker

8


(b)

(c)

(d)

2. (a) The following diagram shows the scale of a vernier calliper when the jaws are closed.

Zero error = …+ 0.02……… cm

(b). The following diagram shows the scale of the same vernier calliper when there are

40 pieces of cardboard between the jaws.

0 5 10

0 1

0 5 1

6 7

0 5 10

4 5 A B

Q P

0 5 10

5 6

0 5 10

0 1

Answer: …7.89 cm…………..

Answer: …4.27 cm…………..

Answer: ……6.28 cm………..

Answer: …0.02 cm…………..

Reading shown = …5.64…….cm

Corrected reading = …5.64 - (+ 0.02)= 5.62……..cm

9


3. Diagram 3 (a) shows the reading on a pair of vernier callipers when its jaws are closed with nothing in between them. Diagram 3(b) shows the reading when it is used to measure the thickness of a piece of wood.

What is the actual thickness of the wood?

Zero error = ………………….. cm

Reading shown = …………………..cm

Actual thickness of the wood = ……………………………….cm

Exercise: Micrometer Screw Gauge

1. (a) Determine the readings of the following micrometer screw gauges.

Zero error = …-0.02…….. mm Zero error = …+0.03…….. mm

(b) Determine the readings of the following micrometer screw gauges.

2. Write down the readings shown by the following micrometer screw gauges. (a) (b)

0 0

45

5

0

0

5

0

0 0 5

15

20

Zero error = +0.03………mm Reading shown = 6.67………..mm

Corrected reading = 6.67-(+0.03)=6.64 mm

400 5

30

0 5 1035

0 5 10

0 cm 1 2

(a)

0 5 10

4 5 6

(b)

-0.05

4.51

4.51- (-0.05) =4.56

10


Answer: …6.88 mm………… Answer: …..12.32 mm…… (c) (d)

Answer:………4.71 mm………… Answer: 9.17 mm…………

Accuracy and consistency in measurements.

1. Accuracy : …………………………………………………………………………………

2. Consistency : ………………………………………………………………………………

3. Sensitivity : …………………………………………………………………………………

………………………… ……………………………..

…………………….. ………………………………

Hands-on activity 1.2 on page 2 of the practical book to determine the sensitivity of some measuring instruments.

Errors in measurements

1. All measurements are values ………………………………………………………………

2. In other word, it is a matter of ……………………………………………………………

The ability of an instrument to measure nearest to the actual value

The ability of an instrument to measure consistently with little or no relative deviation among readings.The ability of an instrument to detect a small change in the quantity measured.

inaccurate but consistent consistent and accurate

Accurate but not consistent inaccurate and not consistent

35

20

250

15

200 5

of approximation only.

how close the measurement is to the actual value.

error exist in all measurements.

Systematic errors

a weakness of the instrument

the difference between reaction time of the brain and the action.

zero error is when the pointer is not at zero when not in use.

Range of the measuring instrument – absolute error .

Reaction time of the brain.

Initial reading is not at the zero scale – zero error

11


3. This is because ……………………………………………………………………………

4. Two main types of errors:

4.1 ……………………………………………

Occurs due to :

a) ………………………………………………………………………………………

b) ………………………………………………………………………………………

c) ………………………………………………………………………………………

Examples :

a) ………………………………………………………………………………………

b) ………………………………………………………………………………………

c) ………………………………………………………………………………………

Absolute error : ………………………………………………………………………………

……….…………………………………………………………………………………………

………………….

Parallax error : ………………………………………………………………………………

Example :

Zero error : …………………………………………………………………………………...

Posit

Positive zero error Negative zero error

Zero error of screw meter gauge

Positive zero error

Zero error =

0 1 cm

0 1 2 3 4 5 6 7 8 9 10

Zero error =

0 1 2 3 4 5 6 7 8 9 10

0 1 cm

Refer to the smallest reading that can be measured by an instrument.

If, the smallest reading = 0.1 cmThen, Absolute error = 0.1 / 2 = 0.05 cm

It occurs because the position of the eye is not perpendicular to the scale of the instrument.

wrong

position of the eye (no error)

wrong

where the pointer is not at zero when not in use

+0.03 cm - 0.04 cm

Correct reading = observed reading – zero error

Zero error of Vernier calliper

Negative zero error

12


4.2 ……………………………………………..

Occurs due to

a) ………………………………………………………………………………………

b) ………………………………………………………………………………………

c) ………………………………………………………………………………………

Example :

a) …………………………………………………………………………………..…

b) ……………………………………………………………………………………..

.....................................................................................................................

1.5 SCIENCETIFIC INVESTIGATION

Steps Explanation

1Making

observation

2Drawing

inferences

3Identifying

and controlling variables

4Formulating a

hypothesis

Horizontal reference Horizontal reference 3 divisions above horizontal reference

2 divisions below horizontal reference

Zero error = + 0.02 mm Zero error = - 0.03 mm

Random error

carelessness in making the measurement.

parallex error , incorrect positioning of the eye when taking the readings.

sudden change of ambient factors such as temperature or air circulation.

Readings are close to the actual value but they are not consistent.

Can be minimized by consistently repeating the measurement at different places in

an identical manner.

Gather all available information about the object or phenomenon to be studied.Using the five senses, sight, hearing, touch, taste and smell.

A conclusion from an observation or phenomena using information that already exist.

Variables are factors or physical quantities which change in the course of a scientific investigation.There are three variables :

i. Manipulated variables – physical quantity which change according to the aim of the experiment.

ii. Responding variables – physicals quantity which is the result of the changed by manipulated variable.

iii. Fixed variables – physicals quantities which are kept constantduring the experiment.

Statement of relationship between the manipulated variable and the responding variable those we would expect.Hypothesis can either be true or false but in correct direction.

i. Conduct an experiment includes the compilation and interpretation of data.

ii. Making a conclusion regarding the validity of the hypothesis.

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5Conducting experiments

Plan and report an experiment

Situation : A few children are playing on a different length of swing in a playground. It is found that the time of oscillation for each swing is different.

Steps Example : refer to the situation above

1 Inference

2 Hypothesis

3 Aim

4 Variables

5 List of apparatus and materials

6 Arrangement of

the apparatus

The period of the oscillation depends on the length of the pendulum.

When the length of the pendulum increases, the period of the oscillation increases.

Investigate the relationship between length and period of a simple pendulum.

Manipulated variable : the length of the pendulum.Responding variable : PeriodFixed variable : the mass of the pendulum and the displacement.

Retort stand with clamp, 100 cm of thread, bob,

l

Retort stand protractor

l

bob

14


7 Procedures

8 Tabulate the data

9

10

11

Analyse the data

Discussion

Conclusion

T / s

1.4

1.2

1.0

0.8

0.6

0.4

0.2

Graf of period, T vs pendulum’s length, l

1. Set up the apparatus as shown in the figure above.2. Measure the length of the pendulum,l = 60.0 cm by using a meter

rule.3. Give the pendulum bob a small displacement 300.Time of

10 oscillations is measured by using a stop watch. 4. Repeat the timing for another 10 oscillations. Calculate the average

time. Period = t10 oscillations 105. Repeat steps 2, 3 and 4 using l = 50.0 cm, 40.0 cm, 30.0 cm and 20.0 cm

1.581.581.501.501.311.311.191.190.990.99

15.815.815.015.013.113.111.911.99.99.9

15.715.715.015.013.113.111.911.99.99.9

15.815.815.015.013.113.111.911.99.99.9

60.060.050.050.040.040.030.030.020.020.0

Period/ s Period/ s(T = t(T = t1010/10)/10)

AverageAverage 2 2 1 1

Length,Length,ll / / cmcm

Time for 10 oscillations / s

0 10 20 30 40 50 60 l / cm

Precautions :1. Oscillation time is measured when the pendulum attained a steady

state.2. Time for 10 oscillations is repeated twice to increase accuracy.3. Discussion (refer to given questions)

The period increases when the length of the pendulum increases. Hypothesis accepted.

15


Reinforcement Chapter 1

Part A :Objective Question

1. Which of the following is a base SI quantity? A Weight B Energy

C Velocity D Mass

2. Which of the following is a derived quantity? A Length B Mass

C Temperature D Voltage

3. Which of the following is not a basic unit?

A Newton B kilogram C ampere D second

4. Which of the following quantities cannot be derived? A Electric current B Power

C Momentum D Force

5. Which of the following quantities is not derived from the basic physical quantity of length?

A Electric charge B Density C Velocity D Volume

6. Initial velocity u, final velocity v, time t and another physical quantity k is related by the equation v - u = kt. The unit for k is

A m s-1 B m-1 s C m s-2 D m2 s-2

7. Which of the following has the

smallest magnitude? A megametre B centimetre

C kilometre D mikrometre

8. 4 328 000 000 mm in standard form is A 4.328 x 10-9 m B 4.328 x 10-6 m

C 4.328 x 106 m D 4.328 x 109 m

9. Which of the following measurements is the longest?

A 1.2 x 10-5 cm B 120 x 10-4 dmC 0.12 mm D 1.2 x 10-11 km

10. The diameter of a particle is 250 µm. What is its diameter in cm?

A 2.5 x 10-2 B 2.5 x 10-4 C 2.5 x 10-6 D 2.5 x 10-8

11. Which of the following prefixes is arranged in ascending order?A mili, senti, mikro, desi

B mikro, mili, senti, desiC mili, mikro, desi, senti

D desi, mikro, mili, senti

12. Velocity, density, force and energy are A basic quantities

B scalar quantitiesC derived quantitiesD vector quantities

13. Which of the following shows the correct conversion of units?

A 24 mm3 =2.4 x 10-6 m3

B 300 mm3=3.0 x 10-7 m3

C 800 mm3=8.0 x 10-2 m3

D 1 000 mm3=1.0 x 10-4 m3

14. Which of the following measurements is the shortest ?

A 3.45 x 103 mB 3.45 x 104 cmC 3.45 x 107 mmD 3.45 x 1012 µm

15. The Hitz FM channel broadcasts radio waves at a frequency of 92.8 MHz in the north region. What is the frequency of the radio wave in Hz?A 9.28 x 104 B 9.28 x 105 C 9.28 x 107 D 9.28 x 1010

16. An object moves along a straight line for time, t. The length of the line, s is

given by the equation 2

2

1gts = . The

SI unit of g is A m2 s2 B m s-2

C s-1 D s-2 m

16


Part B : Structure Question

1. A car moves with an average speed of 75 km h-1 from town P to town Q in 2 hours as shown in Figure 1. By using this information, you may calculate the distance between the two towns.

P Q

Figure 1(a) (i) Based on the statements given, state two basic quantities and their respective SI units.

………………………………………………………………………………………(ii) State a derived quantity and its SI unit.

………………………………………………………………………………………

(b) Convert the value 1 . m to standard form. 5 x 10-3

(c) Complete Table 1 by writing the value of each given prefix.

Table 1(d) Power is defined as the rate of change of work done. Derive the unit for power in

terms of its basic units.

(e) Calculate the volume of a wooden block with dimension of 7 cm, 5 cm breadth and 12 cm height in m3 and convert its value in standard form.

Distance : m and time : s

Speed – m s-1

= 0.2 x 103 m= 2.0 x 102 m

10-9

10-6

106

109

Power =time

work=

time

ntdisplacemeForce × Unit =

s

mkgms ×−2

= kg m2 s-3

Volume = (7 x 10-2) (5 x 10-2) (12 x 10-2) = 420 x 10-6

= 4.20 x 10-4 m3

17


2. Figure 2 shows an ammeter of 0—3 A range.

Figure 2

(a) (i) Name component X. ………………………………………………………………...

(ii) What is the function of X? ………………………………………………………….

(b) Table 2 shows three current readings obtained by three students.

Table 2

(i) Did all the students use the ammeter in Figure2? ..………………………………….(ii) Explain your answer in (b)(i).

………………………………………………………………………………………

3. Figure 3 shows the meniscus of water in a measuring cylinder K, L, and M are three eye positions while measuring the volume of the water.

(a) (i) Which of the eye positions is correct while

taking the reading of the volume of water?

…….……………………………………

Figure 3

(b) The water in the measuring cylinder is replaced with 30 cm3 of mercury.(i) In Figure 4, draw the meniscus of the mercury in the measuring cylinder. Figure 4(ii) Explain why the shape of the meniscus of mercury is as drawn in (b)(i).

No

3rd readings obtained by student 2 and 3 are out of the meter range.

L

The cohesive force is larger than the adhesive force

Mirror

To avoid parallax error

18


………………………………………………………………………………………

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1.1understanding physics physics - ks thong's blog · jpn pahang physics module form 4...

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