Forces, Earth and Space

2. unit of measure for force.
6. simple machine that moves on a pivot point.
8. a natural object that orbits a planet.
10. the part of the boat that is submerged in water.
12. an imaginary line about which something rotates.
13. an orbit around Earth.
15. change position.
16. the repeating path that one object in space takes around another object.
17. the planet on which we live.
18. devices designed to make it easier to move objects.
19. an orbit around the Sun.
20. the force exerted on a mass due to gravity.

1. to move around an axis or centre.
3. simple machine that has a grooved wheel that spins on an axle.
4. causes a change in motion of an object, so that the object moves or slows down or speeds up, or change direction.
5. an instrument that uses shadow to show time.
7. the frictional force air or water exerts against a moving object.
9. a large natural object that orbit a star.
11. when an object has been shaped to reduce friction in air or water.
13. a force exerted on two objects that have mass.
14. a force between two surfaces that are sliding, or trying to slide, across each other.
15. a measure of how much matter is in an object, with the unit of grams or kilograms.
21. simple machine that uses interlocking cogged wheels.