Astronomy - Maths questions

Maths questions often start with the command words 'calculate' or 'determine'. They will then have a blank space for you to show your working. It is important that you show your working, don't just write the answer down. You might earn marks for your working even if you get the answer incorrect.

Some maths questions might ask you to 'show that' something is true. These questions often require you to prove something mathematically. For example, you might have to calculate two values and then compare them.

In some maths questions you will be required to give the units. This may earn you an additional mark. Don't forget to check whether you need to do this.

Maths questions might include graphs and tables as well as calculations. Don't forget to take a ruler and calculator.

If drawing graphs, make sure you:

  1. put the independent variable on the x-axis and the dependent variable on the y-axis
  2. construct regular scales for the axes
  3. label the axes appropriately
  4. plot each point accurately
  5. draw a straight or curved line of best fit (you can use a special best fit line ruler to help with this)

If you are asked to calculate an answer and it has lots of significant figures, you should try to round it to the same number of significant figures you were given in the data in the question. Don't forget to check your rounding.

Edexcel questions courtesy of Pearson Education Ltd.

Sample question 1 - Foundation


Hubble measured the distance of many galaxies from Earth. He also measured the speed at which each galaxy moved away from Earth. Hubble plotted his data on a graph like this.

A graph plotting Hubble’s results showing how fast the galaxy is moving against the distance from earth to the galaxy.

a) Plot the point: distance = 5 units, speed = 4 units. [1 mark]

b) Draw the straight line of best fit. [1 mark]

A graph plotting Hubble’s results showing how fast the galaxy is moving against the distance from earth to the galaxy. The line of best fit is added.

Plot the point in the correct place and then add the straight line of best fit using a ruler. You should aim to have about the same number of points above the line as below the line.

Sample question 2 - Higher


In the figure, the reference wavelength \lambda _0 is shown at 390 nm.

Graphic showing some lines in the absorption spectra from four different galaxies and from a laboratory source. All the spectra are aligned and to the same scale.

a) Estimate the change in the reference wavelength, \Delta \lambda, for the light from galaxy D. [1 mark]

b) Calculate the speed, v, of galaxy D.

v = c \frac{\Delta \lambda}{\lambda _0}

[c = speed of light = 3 × 108 m/s] [2 marks]

a) 410 - 390 = 20 nm

b) Make sure you show your working clearly.

v = \frac{(3 \times 10^{8}) \times (20 \times 10^{-9})}{(390 \times 10^{-9})}

v = 15,400,000 ~m/s