Across
- 2. a small lump of rock orbiting the sun.
- 4. respiratory system
- 5. breakdown of large insoluble food molecules
- 6. amount of force exerted per area.
Down
- 1. resistance to motion of one object moving relative to another.
- 2. type of friction between air and another material.
- 3. the force that attracts a body towards the centre of the earth.