1. Physical Quantities and Units

Question 1

What are the 7 SI units?

Answer 1

1. distance (m)
2. time (s)
3. mass (kg)
4. temperature (K)
5. electric cuurent (A)
6. moles (mol)
7. luminousity (cd)

Question 2

What is the difference between accuracy and precision?

Answer 2

Accuracy refers to how close the measurements are to it’s true value. Precision is how close the measurements are from each other (does not mean it is accurate).

Question 3

What’s the difference between a systematic error and a random error?

Answer 3

Systematic error usually affects accuracy, whilst random error affects precision.

Question 4

How do we find the combined uncertainty of:
6.7 ± 0.1 + 7.2 ± 0.5 ?

Answer 4

In addition, you just add the respective uncertainties.

Therefore, 13.9 ± 0.6

Question 5

How do we find the combined uncertainty of:
2.5 ± 0.2 x 5.5 ± 0.4 ?

Answer 5

c = a x b
𝜎c/c = 𝜎a/a + 𝜎b/b
(where 𝜎 is the uncertainty)

Therefore, 13.75 ± 2.1
–> 13.8 ± 2.1

Question 6

Define scalar quantity

Answer 6

Has magnitude but no direction

Question 7

Define vector quantity

Answer 7

Has magnitude and direction

Question 8

State the derived unit for frequency

Answer 8

s^-1
(Hz)

Question 9

State the derived unit for speed

Answer 9

ms^-1

Question 10

State the derived unit for acceleration

Answer 10

ms^-2

Question 11

State the derived unit for force

Answer 11

kgms^-2
(Newtons/N)

Question 12

State the derived unit for energy

Answer 12

kgm^2 s^-2
(Joules/J)

Question 13

State the derived unit for power

Answer 13

kgm^2 s^-3
(watt/W)

Question 14

State the derived unit for electrical charge

Answer 14

As
(coulomb/c)

Question 15

State the derived unit for potential difference

Answer 15

kgm^2 s^-3 A^-1
(volts/v)

Question 16

State the derived unit for resistance

Answer 16

kgm^2 s^-3 A^-2
(ohm/Ω)

Question 17

State the derived unit for specific heat capacity

Answer 17

m^2 s^-2 K^-1
( Jkg^-1 K^-1 )

Question 18

Multiplying factor of peta-

Answer 18

10^15
(P)

Question 19

Multiplying factor of tera-

Answer 19

10^12
(T)

Question 20

Multiplying factor of giga-

Answer 20

10^9
(G)

Question 21

Multiplying factor of mega-

Answer 21

10^6
(M)

Question 22

Multiplying factor of kilo-

Answer 22

10^3
(k)

Question 23

Multiplying factor of deci-

Answer 23

10^-1
(d)

Question 24

Multiplying factor of centi-

Answer 24

10^-2
(c)

Question 25

Multiplying factor of milli-

Answer 25

10^-3
(m)

Question 26

Multiplying factor of micro-

Answer 26

10^-6
(μ)

Question 27

Multiplying factor of nano-

Answer 27

10^-9
(n)

Question 28

Multiplying factor of pico-