Gravitational Fields Questions

Q2.

(a)

(i) State the relationship between the gravitational potential energy, Ep, and the gravitational potential, V, for a body of mass m placed in a gravitational field.

(1 mark)

(ii) What is the effect, if any, on the values of Ep and V if the mass m is doubled?

(2 marks)

(b)

The diagram above shows two of the orbits, A and B, that could be occupied by a satellite in circular orbit around the Earth, E.

The gravitational potential due to the Earth of each of these orbits is:

orbit A – 12.0 MJ kg–1
orbit B – 36.0 MJ kg–1

(i) Calculate the radius, from the centre of the Earth, of orbit A.

(2 marks)

(ii) Show that the radius of orbit B is approximately 1.1 × 104 km.

(1 mark)

(iii) Calculate the centripetal acceleration of a satellite in orbit B.

(2 marks)

(iv) Show that the gravitational potential energy of a 330 kg satellite decreases by about 8 GJ when it moves from orbit A to orbit B.

(1 mark)

(c) Explain why it is not possible to use the equation Ep = mgh when determining the change in the gravitational potential energy of a satellite as it moves between these orbits.

(1 mark)

(10 marks Total)