A-level Physics (Advancing Physics)/Gravitational Potential/Worked Solutions

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G = 6.67 x 10−11 m3kg−1s−2

g = 9.81 ms−2

1. What is the gravitational potential at the Earth's surface? (mass of Earth = 5.97 x 1024 kg,radius of Earth = 6371 km)

2. Taking the Earth's surface as Vgrav = 0, what is the gravitational potential 2m above the ground?

3. A 0.2 kg firework reaches a gravitational potential relative to the ground of 500Jkg−1. If the firework is 30% efficient, how much energy was expended to get there?

However, this is only 30% of the energy expended, so:

4. Express gravitational potential in terms of gravitational force.

5. Draw the equipotentials and field lines surrounding the Earth.

Gravitational field Earth lines equipotentials.svg