Describe two differences between the orbits of planets and comets.
An astronaut drops a tool on Mars.
State the equation linking gravitational potential energy, mass, ggg and height.
The gravitational field strength (ggg) on Mars is 3.7 N/kg3.7 \text{ N/kg}3.7 N/kg. The mass of the tool is 850 grams850 \text{ grams}850 grams. The tool loses 4.1 J4.1 \text{ J}4.1 J of gravitational potential energy when it falls.
Show that the tool falls through a height of about 1.3 m1.3 \text{ m}1.3 m.
The astronaut then lifts the tool back to its original height.
State the amount of work done in lifting the tool.
Explain why the astronaut would have to do more work to lift the same tool through the same height on Earth.
A weather satellite is in orbit around the Earth.
The satellite orbits the Earth with an orbital radius of 7000 km7000 \text{ km}7000 km and an orbital speed of 7.55 km/s7.55 \text{ km/s}7.55 km/s.
Calculate the number of orbits the satellite makes in one day.
