Astrophysics
4 marks · NormalThe table below shows three planets and their gravitational field strengths:
| Planet | Gravitational field strength (N/kg) |
|---|---|
| Venus | 9 |
| Mars | 4 |
| Jupiter | 23 |
A spacecraft has a mass of 500 kg.
State the formula for calculating the weight of an object on a planet.
Calculate the weight of the spacecraft on Mars and Jupiter. Give your answers in newtons (N).
Explain why the spacecraft would weigh so much more on Jupiter than on Mars, using ideas about planets and gravity.
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.
Show answer
(a) Weight = mass × gravitational field strength
(b) Mars: 2000 N, Jupiter: 11500 N
(c) Jupiter has a much larger mass than Mars, so its gravitational field strength is much higher, making each kilogram weigh more.
Show mark scheme and worked solution
Marking points
B1 (a) · 1 mark · Correctly writes formula for weight as weight = mass × gravitational field strength (or W = m × g).
M1 (b) · 1 mark · Correct calculation for one planet (500 × 4 = 2000 N for Mars or 500 × 23 = 11500 N for Jupiter). (follow-through)
A1 (b) · 1 mark · Correct calculation for both planets. (follow-through)
B2 (c) · 1 mark · Correct explanation that larger mass of Jupiter means a larger gravitational field strength.
Worked solution
a) Weight = mass × gravitational field strength (W = m × g)
b) Mars: 500 kg × 4 N/kg = 2000 N; Jupiter: 500 kg × 23 N/kg = 11500 N
c) Jupiter is much more massive than Mars, so its gravitational field is stronger and objects are heavier on its surface.