Lesson 5.4.3

5.4.3 Planetary motion Quiz: OCR Physics, Unit 4

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson 5.4.3, Planetary motion: 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. What shape is the orbit of a planet according to Kepler's first law?

    • Ellipse
    • Hyperbola
    • Parabola
    • Circle

  2. Where is the Sun situated in a planet's elliptical orbit?

    • At both foci
    • Outside the ellipse
    • At the centre
    • At one focus

  3. What remains constant as a planet sweeps out equal areas in equal times?

    • Linear speed
    • Angular velocity
    • Areal velocity
    • Centripetal force

  4. According to Kepler's second law, when does a planet travel fastest in its orbit?

    • Furthest from Sun
    • Closest to Sun
    • At medium distance
    • At constant speed

  5. What is the relationship between orbital period T and orbital radius r in Kepler's third law?

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

  6. Which force provides the centripetal force required for a planet orbiting the Sun?

    • Magnetic force
    • Gravitational force
    • Electrostatic force
    • Frictional force

  7. What equation gives the orbital speed v of a planet at radius r around mass M?

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

  8. If a planet's orbital radius quadruples, by what factor does its orbital period increase?

    • 16
    • 2
    • 4
    • 8

  9. What is the period of a satellite in a geostationary orbit around Earth?

    • 24 hours
    • 365 days
    • 90 minutes
    • 12 hours

  10. In what direction must a geostationary satellite orbit relative to Earth's rotation?

    • West to east
    • South to north
    • North to south
    • East to west

  11. Where must a geostationary satellite be positioned relative to Earth's surface?

    • Above Greenwich
    • Above the equator
    • At any latitude
    • Above the poles

  12. What happens to the linear speed of a satellite as its orbital radius increases?

    • It decreases
    • It becomes zero
    • It stays constant
    • It increases

  13. How does the mass of an orbiting planet affect its orbital period T?

    • Increases T
    • No effect
    • Decreases T
    • Halves T

  14. What is the unit of the gravitational constant G?

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

  15. What is the orbital period of Earth around the Sun in seconds approximately?

    • 8.64 x 10^4 s
    • 3.15 x 10^7 s
    • 6.02 x 10^23 s
    • 3.15 x 10^5 s

  16. Which graph yields a straight line through the origin for planetary motion?

    • T against r^3
    • T^2 against r^3
    • T against r
    • T^2 against r

  17. What property of a central body determines the gradient of a T^2 against r^3 graph?

    • Radius
    • Mass
    • Temperature
    • Density

  18. If orbital radius r is doubled, what happens to the gravitational force between Sun and planet?

    • Decreases by 4
    • Decreases by 8
    • Decreases by 2
    • Increases by 4

  19. Why do objects in orbit experience apparent weightlessness?

    • They are free-falling
    • No air resistance
    • Gravity is zero
    • Centrifugal force balances

  20. Which type of orbit passes over both the North and South poles of Earth?

    • Equatorial orbit
    • Geostationary orbit
    • Low Earth orbit
    • Polar orbit

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