Introduction Physics, Study notes of Physics

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CHAPTER 1 : INTRODUCTION TO PHYSICS

1.1 Understanding Physics

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 ……………..

Standard Form

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 unit Name of derived unit area area = length x width^ m x m = m^2 – volume volume = length x width x height^ m x m x m = m 3

density – velocity – momentu m

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

Accelerati on

Force force = mass x acceleration^ kg m s^ -2^ Newton (N) pressure weight weight = mass x gravitational acceleration work work = force x displacement power kinetic energy potential energy

P.E = mass x gravitational acceleration x height

Kg ms-2^ Joule (J)

charge charge = current x time Ampere second (As)

Coulomb (C) voltage (^) J C-1^ Volt (v) resistance (^) v A-1^ Ohm (Ω)

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

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 Direction

1. The temperature in the room is 25 0 C
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

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 : ……………………………………………………………………………..

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. ………………………………………………

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 And Micrometer Screw Gauge

1. Write down the readings shown by the following (a)

(b)

(c)

(d)

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

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

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

Answer:………4.71 mm………… Answer: 9. mm…………

6. (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.

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 ……………………………………………………………
3. This is because ……………………………………………………………………………
4. Two main types of errors:

4.1 …………………………………………… Occurs due to : a) ………………………………………………………………………………………

b) ……………………………………………………………………………………… c) ……………………………………………………………………………………… Examples :

a) ……………………………………………………………………………………… b) ……………………………………………………………………………………… c) ……………………………………………………………………………………… Absolute error :

……………………………………………………………………………………….

b) ………………………………………………………………………………… ….. .................................................................................................................

....

1.5 SCIENCETIFIC INVESTIGATION

Steps Explanation 1 Making observation 2 Drawing inferences 3 Identifying and controlling variables 4 Formulating a hypothesis 5 Conducting 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

7 Procedures

8 Tabulate the data 9

Analyse the data

Discussion

Conclusion

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?

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-

(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 m^3 and convert its value in standard form.

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 cm^3 of mercury. (i) In Figure 4, draw the meniscus of the mercury in the measuring cylinder. Figure 4