Lesson 5.4.2

5.4.2 Newton's law of gravitation Quiz: OCR Physics, Unit 4

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson 5.4.2, Newton's law of gravitation: 20 multiple choice questions for the OCR Physics (H156), Unit 4: Newtonian world and astrophysics, written with Revision Ninja.

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The 20 questions

  1. According to Newton's law of gravitation, gravitational force is inversely proportional to what quantity?

    • Separation squared
    • Mass product
    • Mass squared
    • Separation

  2. The unit of the gravitational constant G is:

    • N m^2 kg^2
    • N m kg^-2
    • N m^2 kg^-2
    • kg m^2 s^-1

  3. If the separation between two point masses is doubled, what happens to the gravitational force between them?

    • Four times
    • One quarter
    • One half
    • Double

  4. Two 10 kg masses are 2.0 m apart. What is the gravitational force between them? (G = 6.67 x 10^-11 N m^2 kg^-2)

    • 3.3 x 10^-9 N
    • 1.7 x 10^-9 N
    • 1.7 x 10^-10 N
    • 6.7 x 10^-11 N

  5. Using M = 6.0 x 10^24 kg and r = 6.4 x 10^6 m, the gravitational field strength at the Earth's surface is closest to:

    • 9.8 N/kg
    • 98 N/kg
    • 6.0 N/kg
    • 0.98 N/kg

  6. What property of the gravitational force is represented by the minus sign in Newton's law?

    • It is repulsive
    • It is attractive
    • It is conservative
    • It varies continuously

  7. Near Earth's surface, gravitational field strength is numerically equal to which physical quantity?

    • Free-fall acceleration
    • Terminal velocity
    • Gravitational potential
    • Centripetal acceleration

  8. At a height above the surface equal to Earth's radius, the field strength is approximately:

    • 2.45 N/kg
    • 9.8 N/kg
    • 1.2 N/kg
    • 4.9 N/kg

  9. Which unit is correct for gravitational field strength computed as g = GM/r^2?

    • N s kg^-1
    • kg m^-1
    • N m^2 kg^-1
    • N kg^-1

  10. What term describes the gravitational field close to the Earth's surface?

    • Uniform
    • Zero
    • Radial
    • Inverse square

  11. The gravitational field strength at 1.5 x 10^11 m from a star of mass 2.0 x 10^30 kg is about:

    • 1.3 x 10^1 N/kg
    • 5.9 x 10^-3 N/kg
    • 6.7 x 10^-11 N/kg
    • 5.9 x 10^-5 N/kg

  12. A 5 kg mass and a 10 kg mass attract each other. How do the gravitational forces compare?

    • Zero on both
    • Equal and opposite
    • Larger on 5 kg
    • Larger on 10 kg

  13. If both masses in a gravitational pair are doubled while the separation is unchanged, the force becomes:

    • 2 times as large
    • 8 times as large
    • unchanged
    • 4 times as large

  14. The field strength at a distance of 3R from a planet's centre, compared with its surface value, is:

    • one sixth
    • one third
    • one ninth
    • one twenty-seventh

  15. A point mass gives a field strength of 4.0 N/kg at distance r. What is the field strength at distance 2r?

    • 0.5 N/kg
    • 1.0 N/kg
    • 8.0 N/kg
    • 2.0 N/kg

  16. A 70 kg astronaut is 400 km above the Earth's surface, where g is about 8.7 N/kg. What is the astronaut's weight?

    • 690 N
    • 9.8 N
    • 610 N
    • 540 N

  17. Which expression gives the mass of a planet from its surface field strength g and radius R?

    • M = gR/G
    • M = GgR
    • M = G/(gR^2)
    • M = gR^2/G

  18. In which direction does the gravitational force act on an object near Earth's surface?

    • Towards Earth's centre
    • Away from centre
    • Parallel to surface
    • Along the equator

  19. Planet A has twice the radius of Planet B, with equal density. What is surface field strength g_A / g_B?

    • Half
    • Four times
    • Eight times
    • Double

  20. If both the mass and radius of a planet are doubled, how does its surface field strength change?

    • Unchanged
    • Halved
    • Doubled
    • Quartered

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