Module 2 – Foundations of physics

Question 1

What are the 7 SI base units?

Answer 1

Question 2

Explain what is meant by a ‘random error’.

Answer 2

Random errors can occur when any measurement is being made, and are measurement errors where the measurements vary unpredictably. They can be caused by external factors affecting the environment, which it may not be possible to control, and also by difficulty in reading a measuring device and deciding the value it shows.

Question 3

Explain what is meant by a ‘systematic error’.

Answer 3

Systematic errors are measurement errors in which the measurement differs from the true value by a consistent amount each time. This could be caused by the way in which measurements are taken, or by a faulty measuring device. It is possible to correct for systematic errors.

Question 4

What is the formula for absolute uncertainty?

Answer 4

± (Range of measurements/2).

Question 5

What is the formula for percentage uncertainty?

Answer 5

(Absolute Uncertainty / Actual Value) * 100

Question 6

Describe how an ideal line of best fit is drawn.

Answer 6

When the line of best fit is drawn, it must pass within all of the error bars, and have a balanced number of data points on each side.

Question 7

Describe how a worst line of best fit is drawn.

Answer 7

This is the least acceptable line passing through all of the error bars (usually the shallowest or most steep line possible).

Question 8

Describe how a best and worst line of best fit can be used to calculate percentage uncertainty.

Answer 8

(Gradient of LOBF - Gradient of WLOBF) / Gradient of LOBF * 100