Introduction Physics, Study notes for Physics. Mercy College (NY)

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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

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 :

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 unit Name 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 –

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 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

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 : ……………………………………………………………………………..

2. Measuring cylinder : ……………………………………………………....................

3. Ruler : ………………………………………………………………………………………

wrong right wrong

10 11 12 13 14 15 Reading = ……………… cm

4. Vernier calliper

A venier calliper is used to measure :

a. ………………………………………………

b. ………………………………………….

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

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 :

……………………… …………………… ……………………… ………..

………………………. …………………….. ………………

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.

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.

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

(c) (d)

4. (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.

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

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 :

……………………………………………………………………………………….

………………………………………………………………………………………………

…………….

Example :

Parallax error :

………………………………………………………………………………

Zero error : …………………………………………………………………………………... Correct reading = observed reading – zero error

Positive zero error negative zero error

2. …………………………………………….. Occurs due to

a) ……………………………………………………………………………………… b) ……………………………………………………………………………………… c) ………………………………………………………………………………………

Example : a) ………………………………………………………………………………….. …

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

10

11

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?

A Length B Mass C Temperature D Voltage

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

A Newton B kilog ram 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 centi

metre 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 dm C 0.12 mm D 1.2 x 10-11 km

10. The diameter of a particle is 250 F 06 Dm. 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, desi

C mili, mikro, desi, senti D desi, mikro, mili, senti

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

B scalar quantities C derived quantities D 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 m B 3.45 x 104 cm C 3.45 x 107 mm D 3.45 x 1012 F 06 Dm

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 . The SI unit of g is A m2 s2 B m s-2 C s-1 D s-2 m

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.

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? .. ………………………………….

………………………………………………………………………… ……………

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).

………………………………………………………………………………………