Lesson 3.7.2.2

3.7.2.2 Gravitational field strength Quiz: AQA Physics, Unit 7

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson 3.7.2.2, Gravitational field strength: 20 multiple choice questions for the AQA Physics (7408), Unit 7: Fields and their consequences (A-level only), written with Revision Ninja.

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The 20 questions

  1. Gravitational field strength at a point is defined as:

    • mass per unit force
    • force per unit mass
    • energy per unit mass
    • force per unit volume

  2. The gravitational field strength in a radial field at distance r from a mass M is:

    • g = GM / r^2
    • g = GM / r
    • g = G M^2 / r^2
    • g = GM r^2

  3. Gravitational field lines point:

    • towards the mass producing the field
    • away from the mass producing the field
    • around the mass in closed loops
    • tangent to the surface of the mass

  4. Near the Earth's surface, gravitational field strength is approximately constant because:

    • the Earth's gravity is zero near the surface
    • g is always 9.8 at all distances
    • the distance moved is very small compared with the Earth's radius
    • field lines are parallel only because of rotation

  5. The SI unit of gravitational field strength is:

    • N m^-1
    • N kg^-1, equivalent to m s^-2
    • N s kg^-1
    • kg m^-1

  6. The approximate value of gravitational field strength at the Earth's surface is:

    • 9.8 N kg^-1
    • 9.8 N
    • 98 N kg^-1
    • 0.98 N kg^-1

  7. Which description of gravitational field strength outside a uniform planet is correct?

    • g is constant at all distances
    • g falls as 1/r outside the planet
    • g falls with the inverse square of distance from the centre
    • g increases linearly with distance from the centre

  8. Gravitational field strength at Earth's surface is 9.8 N kg^-1. What is it at a height where the distance from the centre is twice the radius?

    • about 19.5 N kg^-1
    • about 2.4 N kg^-1
    • about 4.9 N kg^-1
    • about 1.2 N kg^-1

  9. Estimate the gravitational force on a 70 kg person at Earth's surface.

    • about 7.1 N
    • about 140 N
    • about 6900 N
    • about 690 N

  10. Mars has mass 6.4 x 10^23 kg and radius 3.4 x 10^6 m. Estimate the field strength at its surface (G = 6.67 x 10^-11).

    • about 3.7 N kg^-1
    • about 0.37 N kg^-1
    • about 1.6 N kg^-1
    • about 9.8 N kg^-1

  11. An object of mass 500 kg is placed where g = 4.0 N kg^-1. What is its weight?

    • 2000 N
    • 20000 N
    • 125 N
    • 200 N

  12. Two equal masses of 2.0 kg are 1.0 m apart. What is the net gravitational field strength at the midpoint between them?

    • twice the field of one mass
    • four times the field of one mass
    • zero, since the two fields are equal and opposite
    • equal to the field of one mass

  13. A 0.50 kg object experiences a gravitational force of 4.9 N. What is the gravitational field strength at its position?

    • 4.9 N kg^-1
    • 9.8 N kg^-1
    • 0.10 N kg^-1
    • 2.45 N kg^-1

  14. Gravitational field strength is greater in a region where field lines are:

    • absent
    • further apart
    • parallel and equally spaced
    • closer together

  15. How does g change when the distance from the centre of a planet doubles, outside the planet?

    • It is unchanged
    • It doubles
    • It decreases to one quarter
    • It halves

  16. A mass moves from Earth's surface to the Moon. Which quantity does NOT change?

    • the gravitational force on it
    • weight
    • mass
    • the gravitational field strength at its location

  17. A planet has the same density as Earth but twice Earth's radius. How does its surface field strength compare with Earth's?

    • twice Earth's
    • half Earth's
    • unchanged
    • four times Earth's

  18. On an Earth-like planet where g = 9.8 N kg^-1 at the surface, estimate g at a distance of 3 times the radius from the centre.

    • about 1.1 N kg^-1
    • about 3.3 N kg^-1
    • about 0.33 N kg^-1
    • about 2.5 N kg^-1

  19. A student claims that g is 9.8 N kg^-1 everywhere in the universe. Which response is best?

    • Correct: g depends only on the mass of the observer.
    • Incorrect: g is zero everywhere except at Earth's surface.
    • Correct: g is a universal constant equal to 9.8 N kg^-1.
    • Incorrect: g depends on the mass producing the field and the distance from its centre, so it varies; 9.8 N kg^-1 applies only at Earth's surface.

  20. A graph of g against 1/r^2 for a point mass is a straight line. What is its gradient?

    • M / G
    • G / M
    • GM
    • GM^2

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