Science 7 · Unit 3: Forces and energy · Cambridge Lower Secondary Science Stage 7

Questions

1. 1. A planet orbits the Sun. In which direction does the Sun's gravity pull the planet?

   • towards the centre of the Sun
   • in the direction the planet is moving
   • away from the Sun
   • towards the next planet
   Check

2. 2. Why does a planet keep moving in a curved orbit instead of a straight line?

   • Its engines steer it.
   • The planet has no mass.
   • The Sun's gravity keeps pulling it towards the Sun, changing its direction.
   • Air resistance pushes it round.
   Check

3. 3. A spacecraft travels from the Moon to Earth through space, where there are no particles. What is a space with no particles called?

   • a vacuum
   • a gas
   • a liquid
   • a solid
   Check

4. 4. Which force slows a spacecraft in the air near Earth, but does not act on it in space?

   • air resistance
   • gravity
   • weight
   • pull
   Check

5. 5. Spacecraft launched in the 1970s have no engines, yet they keep moving at a constant speed. Why?

   • There is no air resistance in space.
   • They have no mass.
   • They have no energy.
   • They have no weight.
   Check

6. 6. Why is there no air resistance in space?

   • Space is too cold.
   • Gravity cancels it out.
   • Space is a vacuum, with no air particles to push against.
   • Spacecraft are too fast.
   Check

7. 7. Saturn's rings are made of millions of pieces of rock. Which force keeps each piece in orbit?

   • Saturn's gravity, pulling towards the centre of Saturn
   • the Sun's gravity, pulling towards the Sun
   • air resistance from Saturn's atmosphere
   • magnetism from the rocks
   Check

8. 8. Why does a rocket need very powerful engines to go from Earth into space?

   • to overcome Earth's gravity
   • to push against the vacuum of space
   • to keep the astronauts warm
   • to make sound energy
   Check

9. 9. When the Space Shuttle came back to Earth, its speed decreased very suddenly, but most of the force for slowing it did not come from engines. What slowed it down?

   • air resistance in Earth's atmosphere
   • Earth's gravity
   • friction with space
   • the Moon's gravity
   Check

10. 10. Voyager 2 had no engines. It passed close by Jupiter, then continued its journey to Saturn. What happened to its path as it passed Jupiter?

    • It curved towards Jupiter, then carried on.
    • It carried on in a straight line.
    • It curved away from Jupiter.
    • It stopped next to Jupiter.
    Check

11. 11. Comets and asteroids also orbit the Sun. What keeps them in orbit?

    • the force of gravity from the Sun
    • their engines
    • air resistance
    • the force of gravity from the Earth
    Check

12. 12. The Sun has the strongest gravity in the Solar System. Which object is likely to have the second strongest gravity?

    • Jupiter, the planet with the largest mass
    • the Moon, because it is nearest to us
    • the Earth, because we live on it
    • Mercury, because it is closest to the Sun
    Check

13. 13. Which of these forces acts on the Earth as it orbits the Sun?

    • gravity, air resistance and friction
    • gravity and air resistance
    • air resistance only
    • gravity only
    Check

14. 14. True or false: Gravity does not act in space.

    • True
    • False
    Check

15. 15. Which planet orbits the Sun with the highest speed?

    • Neptune, because it is the furthest from the Sun
    • Jupiter, because it has the largest mass
    • Earth, because it has the most water
    • Mercury, because it is closest to the Sun and has the strongest pull from the Sun's gravity
    Check

16. 16. What happens to the Sun's gravity as the distance from the Sun increases?

    • It disappears completely after Earth.
    • It gets stronger.
    • It stays the same.
    • It gets weaker.
    Check

17. 17. What happens to the air resistance on an object as it moves faster?

    • It stays the same.
    • It gets smaller.
    • It gets greater.
    • It disappears.
    Check