Lesson 3.7.2.4

3.7.2.4 Orbits of planets and satellites Quiz: AQA Physics, Unit 7

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson 3.7.2.4, Orbits of planets and satellites: 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. For a satellite in a circular orbit of radius r about a body of mass M, the orbital speed is:

    • v = sqrt(GM r)
    • v = GM / r
    • v = GM / sqrt(r)
    • v = sqrt(GM / r)

  2. Kepler's third law for circular orbits states that:

    • T^2 is proportional to r^3
    • T^2 is proportional to r
    • T is proportional to r^3
    • T is proportional to r

  3. The total energy of a satellite in a circular orbit of radius r is:

    • positive, E = +GMm / (2r)
    • negative, E = -GMm / (2r)
    • E = GMm r
    • E = -GMm / r

  4. For a satellite in a circular orbit, its kinetic energy is:

    • equal to the magnitude of its gravitational potential energy
    • negative for any bound orbit
    • zero
    • GMm / (2r), half the magnitude of its gravitational potential energy

  5. The escape velocity from a body of mass M and radius r is:

    • v = sqrt(2GM / r)
    • v = sqrt(GM / (2r))
    • v = sqrt(GM / r)
    • v = 2GM / r

  6. A synchronous (geostationary) satellite:

    • has a period equal to Earth's rotation period of 24 hours and orbits in the equatorial plane
    • has a period of 24 hours and orbits over the poles
    • has a period of 1 hour and orbits in the equatorial plane
    • has a period of 12 hours and orbits above the equator

  7. Satellites in low Earth orbit are typically:

    • close to the Earth, with periods of about 90 minutes
    • stationary above a fixed point on Earth
    • above 36 000 km with a period of 24 hours
    • at the distance of the Moon

  8. A satellite orbits at radius 4.2 x 10^7 m about Earth, where GM = 4.0 x 10^14 m^3 s^-2. Estimate its period.

    • about 12 hours
    • about 240 hours
    • about 1.5 hours
    • about 24 hours

  9. A satellite orbits at radius 7.0 x 10^6 m about Earth, where GM = 4.0 x 10^14 m^3 s^-2. What is its orbital speed?

    • about 11 km s^-1
    • about 5.3 km s^-1
    • about 7.6 km s^-1
    • about 3.8 km s^-1

  10. Using GM = 4.0 x 10^14 m^3 s^-2 and Earth's radius 6.4 x 10^6 m, estimate the escape velocity from the surface.

    • about 5.6 km s^-1
    • about 11 km s^-1
    • about 7.9 km s^-1
    • about 15.8 km s^-1

  11. A 1000 kg satellite orbits at radius 7.0 x 10^6 m where GM = 4.0 x 10^14 m^3 s^-2. What is its total energy?

    • about +2.9 x 10^10 J
    • about -2.9 x 10^10 J
    • about -1.4 x 10^7 J
    • about -5.7 x 10^10 J

  12. The orbital radius of a satellite is doubled. Its orbital period becomes approximately:

    • 4 times greater
    • 1.4 times greater
    • 2 times greater
    • 2.8 times greater

  13. Compared with the orbital speed of a satellite at a given radius, the escape speed from that radius is:

    • twice as great
    • about 1.4 times greater
    • equal
    • half as great

  14. On a log-log plot of period T against orbital radius r for planets orbiting the same star, the gradient is:

    • 0.5
    • 2
    • 1.5
    • 3

  15. Which statement about orbits is correct?

    • Higher orbits have shorter periods and higher speeds
    • Higher orbits have longer periods and lower orbital speeds
    • Orbital speed is independent of radius
    • Higher orbits have the same speed but longer periods

  16. A satellite moves from a higher circular orbit to a lower one. Its kinetic energy:

    • becomes zero
    • stays the same
    • decreases, because its speed decreases
    • increases, because its speed increases

  17. A satellite in a circular orbit at radius r1 moves to a circular orbit at radius 4 r1. Its period increases by a factor of:

    • 16
    • 2
    • 4
    • 8

  18. A 500 kg satellite is in circular orbit at radius 8.0 x 10^6 m, where GM = 4.0 x 10^14 m^3 s^-2. How much energy must be supplied to move it to infinity?

    • about 1.3 x 10^10 J
    • about 1.3 x 10^7 J
    • about 2.5 x 10^10 J
    • about 6.3 x 10^9 J

  19. A student says astronauts in orbit are weightless because there is no gravity in space. Which response is best?

    • Incorrect: weightlessness results only from air resistance.
    • Correct: gravity acts only on objects that are not moving.
    • Correct: there is no gravity beyond the atmosphere.
    • Incorrect: gravity still acts on them; they are in free fall, continually accelerating towards Earth, which causes the sensation of weightlessness.

  20. Using GM = 4.0 x 10^14 m^3 s^-2 and a period of 24 hours, estimate the radius of a geostationary orbit.

    • about 3.8 x 10^8 m
    • about 1.0 x 10^5 m
    • about 4.2 x 10^7 m
    • about 6.4 x 10^6 m

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