Physical Quantities, Units and Measurements

Question 1

Precision of Metre Rule/Measuring Tape

Answer 1

0.1cm

Question 2

Precision of Digital Vernier Calipers

Answer 2

0.001cm

Question 3

Precision of Digital Micrometer Screw Gauge

Answer 3

0.0001cm

Question 4

Precision of Atomic Clock

Answer 4

10⁻¹⁰ s

Question 5

Precision of Digital Stopwatch

Answer 5

+/- 0.01s

Question 6

Precision of Analogue Stopwatch

Answer 6

+/- 0.1s

Question 7

Precision of Ticker-tape timer

Answer 7

0.02s

Question 8

Human reaction time

Answer 8

200ms

Question 9

Purpose of Inside Jaws of Digital Vernier Calipers

Answer 9

To measure the internal diameter of objects

Question 10

Purpose of Outside Jaws of Digital Vernier Calipers

Answer 10

To measure external diameter/width of objects

Question 11

Purpose of Tail of Digital Vernier Calipers

Answer 11

To measure depth of objects

Question 12

Purpose of Spindle in Digital Micrometer Screw Gauge

Answer 12

To measure diameter of objects

Question 13

Purpose of Ratchet in Digital Micrometer Screw Gauge

Answer 13

To adjust the spindle to ensure spindle is in contact with object

Question 14

What does a Metre Rule/Measuring Tape measure?

Answer 14

It measures a person’s waist/height of table

Question 15

What does a Digital vernier Caliper measure?

Answer 15

It measures the diameter of test tube

Question 16

What does a Digital Micrometer Screw Gauge measure?

Answer 16

It measures the diameter of a wire

Question 17

What is a Random Error?

Answer 17

Random Errors are unpredictable and cluster around a mean value

Question 18

What is a Systematic Error?

Answer 18

Systematic Errors are constant and predictable

Question 19

How to minimise Random Errors?

Answer 19

Random Errors can be minimised by taking several readings and taking the average

Question 20

How to avoid Systematic Errors?

Answer 20

Systematic Errors can be avoided by calibrating equipment, which if not corrected, can lead to values far from true value

Question 21

What causes Parallax Error?

Answer 21

Parallax Error is caused when our eyes are positioned such that our line of sight is not perpendicular to the ruler

Question 22

Why do we avoid using zero mark as start point for measurements?

Answer 22

As wear and tear makes it unsuitable for measuring purposes and it may introduce errors to readings

Question 23

Example of Random Error

Answer 23

Human reaction time

Question 24

Example of Systematic Error

Answer 24

Always reads from the top of the meniscus instead of the bottom

Question 25

Examples of Scalar Quantities

Answer 25

Distance, Speed, Mass, Energy, Time

Question 26

Examples of Vector Quantities

Answer 26

Displacement, Velocity, Weight, Acceleration, Force

Question 27

SI Unit for Length

Answer 27

Metres

Question 28

SI Unit for Mass

Answer 28

Kilograms

Question 29

SI Unit for Time

Answer 29

Seconds

Question 30

SI Unit for Electric Current

Answer 30

Ampres

Question 31

SI Unit for Thermodynamic Temperature

Answer 31

Kelvin

Question 32

SI Unit for Amount of Substance

Answer 32

Mol

Question 33

Prefixes

Answer 33

Tera: 10¹² (T)
Giga: 10⁹ (G)
Mega: 10⁶ (M)
Kilo: 10³ (k)
Deci: 10⁻¹ (d)
Centi: 10⁻² (c)
Milli: 10⁻³ (m)
Micro: 10⁻⁶ (µ)
Nano: 10⁻⁹ (n)
Pico: 10⁻¹² (p)

Question 34

What is One Complete Oscillation of a Pendulum?

Answer 34

1 complete to-and-fro motion of pendulum

Question 35

What is the Period of a Pendulum?

Answer 35

Time taken for 1 complete oscillation

Question 36

What affects/does not affect the Period of a Pendulum?

Answer 36

Mass of bob does not affect period
Gravitational field strength and length of pendulum affects period

Question 37

How to measure One Complete Oscillation of a Pendulum?

Answer 37

Measure time for 20 oscillations and divide by 20