Astrophysics
4 marks · EasyThe diagram below shows part of our solar system, with the Sun, the Earth, and an artificial satellite orbiting Earth.
What keeps the satellite in orbit around the Earth? State the force.
Name the unit used to measure the gravitational field strength on the surface of a planet.
Is the strength of gravity greater on Earth or on the Moon? Explain briefly.
Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.
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(a) Gravity (gravitational force)
(b) N/kg
(c) Earth (gravity is stronger because its mass is more/field strength is higher) · must show comparison made, correct explanation (mass/field strength)
Show mark scheme and worked solution
Marking points
B1 (a) · 1 mark · Gravity (or gravitational force) named correctly
B1 (b) · 1 mark · Unit N/kg stated correctly
B1 (c) · 1 mark · Correct answer: Earth
B1 (c) · 1 mark · Correct explanation: higher mass or higher gravitational field strength
Worked solution
a) The force that keeps the satellite in orbit is gravity (gravitational force).
b) The unit of gravitational field strength is newton per kilogram (N/kg).
c) The strength of gravity is greater on Earth because Earth has more mass, so its gravitational field strength is higher than on the Moon.