David Sang and Graham Jones Solutions for Chapter: Gravitational Fields, Exercise 9: EXAM-STYLE QUESTIONS

Consider the dwarf planet Pluto to be an isolated sphere of radius $1.2\times {10}^6\mathrm{m}$ and mass of $1.27\times {10}^{22}\mathrm{kg}.$What is the gravitational potential at the surface of Pluto?

Calculate Charron's orbital period.

Explain why Pluto's orbital period must be the same as Charron's.

This diagram shows the variation of the Earth's gravitational field strength with distance from its centre.

Determine the gravitational field strength at a height equal to $2R$ above the Earth's surface, where $R$is the radius of the Earth.

This diagram shows the variation of the Earth's gravitational field strength with distance from its centre.

 A satellite is put into an orbit at this height. State the centripetal acceleration of the satellite. 

This diagram shows the variation of the Earth's gravitational field strength with distance from its centre.

Calculate the speed at which the satellite must travel to remain in this orbit.

This diagram shows the variation of the Earth's gravitational field strength with distance from its centre.

Frictional forces mean that the satellite gradually slows down after it has achieved a circular orbit. Draw a diagram of the initial circular orbital path of the satellite, and show the resulting orbit as frictional forces slow the satellite down. 

This diagram shows the variation of the Earth's gravitational field strength with distance from its centre.

Suggest and explain why there is not a continuous bombardment of old satellites colliding with the Earth.