Lesson 12.2.1

12.2.1 Gravitational potential of a point mass Quiz: Pearson Edexcel Physics, Unit 12

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson 12.2.1, Gravitational potential of a point mass: 20 multiple choice questions for the Pearson Edexcel Physics (9PH0), Unit 12: Gravitational Fields, written with Revision Ninja.

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The 20 questions

  1. What is gravitational potential at a point?

    • The kinetic energy of a mass at rest at that point.
    • The work done per unit time to move a mass.
    • The force per unit mass at that point.
    • The work done per unit mass to move a small mass from infinity to that point.

  2. What value of gravitational potential is taken as the reference?

    • Zero, at the surface of the Earth.
    • Minus one, at the centre of the mass.
    • Zero, at infinity.
    • One, at a distance of one metre.

  3. Which equation gives the gravitational potential at distance r from a point mass M?

    • V = - G M / r^2
    • V = G M / r
    • V = - G M / r
    • V = G M r

  4. What are the SI units of gravitational potential?

    • N kg^-1
    • kg J^-1
    • J m^-1
    • J kg^-1

  5. Why is the gravitational potential near a mass negative?

    • Mass is negative in sign, so the gravitational potential must also be negative everywhere.
    • Potential is negative only at the Earth's surface, not elsewhere in space around planets.
    • Zero is set at infinity, and gravity does work as mass falls in, lowering its energy.
    • Gravity pushes masses apart at all distances, which lowers the potential near them.

  6. Earth's mass is 6.0 x 10^24 kg. What is the gravitational potential at a distance of 2.0 x 10^7 m from its centre? Use G = 6.67 x 10^-11 N m^2 kg^-2.

    • -2.0 x 10^7 J kg^-1
    • -2.0 x 10^-7 J kg^-1
    • -3.3 x 10^7 J kg^-1
    • +2.0 x 10^7 J kg^-1

  7. Using the same Earth, how much work must be done to move a 5.0 kg mass from 2.0 x 10^7 m to 4.0 x 10^7 m from its centre?

    • -5.0 x 10^7 J
    • 5.0 x 10^7 J
    • 1.0 x 10^7 J
    • 2.0 x 10^8 J

  8. The potential at distance r from a point mass is -40 J kg^-1. What is the potential at distance 2r?

    • -10 J kg^-1
    • -40 J kg^-1
    • -20 J kg^-1
    • -80 J kg^-1

  9. Earth's mass is 6.0 x 10^24 kg. Using 6.67 x 10^-11 N m^2 kg^-2, how much energy per kilogram is needed to move from Earth's surface radius 6.4 x 10^6 m to infinity?

    • about 6.3 x 10^6 J kg^-1
    • about 6.3 x 10^7 J kg^-1
    • about 9.8 J kg^-1
    • about 1.3 x 10^8 J kg^-1

  10. Two equal point masses of 1000 kg are 4.0 m apart. What is the gravitational potential at their midpoint?

    • 0 J kg^-1
    • -1.3 x 10^-7 J kg^-1
    • -3.3 x 10^-8 J kg^-1
    • -6.7 x 10^-8 J kg^-1

  11. A 10 kg mass is at a point where the gravitational potential is -2.0 x 10^7 J kg^-1. What is its gravitational potential energy?

    • -2.0 x 10^8 J
    • -2.0 x 10^6 J
    • 2.0 x 10^8 J
    • -2.0 x 10^7 J

  12. What is the minimum speed needed for a body to escape from Earth's surface, given GM/R = 6.25 x 10^7 J kg^-1?

    • about 2.2 x 10^4 m s^-1
    • about 7.9 x 10^3 m s^-1
    • about 1.1 x 10^4 m s^-1
    • about 1.1 x 10^3 m s^-1

  13. A 2.0 kg object is raised by 1.0 m near Earth's surface, where the change in potential is g h. What is the increase in gravitational potential energy?

    • 9.8 J
    • 19.6 J
    • 0.2 J
    • 2.0 J

  14. Why is the approximation Δ V = g Δ h only valid for small heights near a surface?

    • The potential is zero at the surface, so the approximation holds only there.
    • Gravity is constant at all distances from any mass.
    • Potential energy is always proportional to height for any distance.
    • Over small heights the gravitational field is approximately uniform, so g is almost constant.

  15. Why must work be done to move a mass away from a planet?

    • The planet pushes the mass away, so the mass must be pulled back.
    • Mass loses energy when it moves away from a planet.
    • The gravitational force is attractive, so the mass gains potential energy as it moves away.
    • Gravity is repulsive at large distances, so work is needed.

  16. Why is gravitational potential energy negative for a bound system?

    • The energy of a bound system is always exactly zero, whatever the masses or separation.
    • Energy must be supplied to separate the masses, and infinity is defined as zero energy.
    • The masses have negative mass in a bound system, so their total energy is negative overall.
    • Gravity is repulsive inside a bound system, so the energy of the masses is negative.

  17. A mass moves from infinity to a point nearer a planet. Which statement is correct?

    • The potential becomes more positive as the mass moves in, and the field does negative work.
    • The potential becomes more negative, and the field does positive work on the mass.
    • The potential is unchanged overall, since the mass itself has not changed at all.
    • The field does no work because gravity is conservative only near the surface of the planet.

  18. A body at the surface of a planet of mass M and radius R is given enough speed to escape. Which expression gives this escape speed?

    • v = sqrt(2 G M / R)
    • v = 2 G M / R
    • v = sqrt(G M / R)
    • v = G M / R

  19. A 3.0 kg mass moves to a point where its gravitational potential increases by 5.0 J kg^-1. What is the change in its gravitational potential energy?

    • 15 J
    • 5.0 J
    • 1.7 J
    • -15 J

  20. Which description of gravitational potential against distance from a point mass is correct?

    • It is positive and decreases steadily to zero at infinity, never becoming negative.
    • It falls without limit as distance increases, becoming more and more negative with distance.
    • It is negative, rises towards zero as distance increases, and reaches zero at infinity.
    • It is a straight line through the origin, with a constant gradient at every distance.

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