Topic 1: ​Measurement and uncertainties​

Question 1

What are the 6 fundamental SI units? (Hint, they are for the following quantities:)
- mass
- distance
- time
- electrical current
- amount of substance
- temperature

Answer 1

• Kilogram (kg)
• Meter (m)
• Second (s)
• Ampere (A)
• Mole (mol)
• Kelvin (K)

Question 2

Convert N to SI units.

Answer 2

kg m / s^2

Question 3

Convert J to SI units.

Answer 3

kg m^2 / s^2

Question 4

What is the speed of light?

Answer 4

3 * 10^8 m

Question 5

What are the only 2 scenarios when figures aren’t significant?

Answer 5

• in a number with a decimal point, all leading zeros are insignificant e.g. 0.015 has 2 s.f.
• in a whole number, any trailing zeros are insignificant
  e.g. 750 has 2 s.f.
• however any zeros that are not leading after a decimal point are significant
  e.g. 0.0100 has 3 s.f.

Question 6

When multiplying or dividing numbers, how many significant figures should you use?

Answer 6

You should not exceed the least precise value of the calculation and any answer any answer should be consistent with the number of significant figures of the given data in the question.

Question 7

In multiplication/division, give the answer to the lowest __________.

Answer 7

Significant figure (S.F.)

Question 8

In addition/subtraction, give the answer to the lowest ___________.

Answer 8

Decimal place (D.P.)

Question 9

What are estimations often rounded to?

Answer 9

The nearest order of magnitude (power of 10)

Question 10

What are orders of magnitude?

Answer 10

Numbers given in powers of 10 that are used to compare the size of physical data.

Question 11

What is the cause of a random error?

Answer 11

Fluctuations in measurements centred around the true value (spread).

Question 12

What is the cause of a systematic error?

Answer 12

Fixed shifts in measurements away from the true value.

Question 13

What is the cause of a systematic error?

Answer 13

Fixed shifts in measurements away from the true value.

Question 14

Which error is caused by bias?

Answer 14

Systematic error

Question 15

Which error can be reduced by averaging over repeated measurements?

Answer 15

Random error

Question 16

Which errors are the following scenarios?
- Fluctuations in room temperature
- The noise in circuits
- Incorrect method of measurement
- Human error
- Equipment calibration error such as the zero offset error

Answer 16

• Random error
• Random error
• Systematic error
• Random error
• Systematic error

Question 17

What does an absolute uncertainty look like?

Answer 17

±Δx

Question 18

What does a fractional uncertainty look like?

Answer 18

±Δx / x

Question 19

What does a percentage uncertainty look like?

Answer 19

±Δx / x * 100

Question 20

What would the uncertainty be for the following:
- y = a + b
- y = a * b
- y = a / b
- y = a - c
- y = a^b

Answer 20

• Δy=Δa+Δb (sum of absolute uncertainties)
• Δy/y=Δa/a+Δb/b (sum of fractional uncertainties)
• Δy/y=Δa/a+Δb/b (sum of fractional uncertainties)
• Δy=Δa+Δb (sum of absolute uncertainties)
• Δy/y=|n|Δa/a (|n| times fractional uncertainty)

Question 21

What do error bars on a graph indicate?

Answer 21

Uncertainties

Question 22

ADD QUESTIONS ON UNCERTAINTIES IN GRAPHS

Question 23

What is a scalar quantity?

Question 24

What is a vector quantity?

Question 25

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