Across

1. Tiny pieces of matter
6. The opposite of an operation or action
7. The gaseous layer surrounding the planet Earth
8. A point about which something turns - a lever for example
10. Something that causes an object to change speed or direction
12. The state of matter where particles are far apart and move quickly
13. Transmission of compressive forces by a liquid
14. A gas or liquid
15. The height of liquid in a container

Down

1. The total force applied divided by the area on which it acts
2. The state of matter where particles are close together but can move past eachother
3. The contents of the Earth's oceans
4. Torque - the product of the applied force and the perpendicular distance to the axis
5. Totally resistant to being squashed
7. The gaseous layer on a planet
8. The unit of pressure - one newton per square metre
9. The state of matter where particles are close together and cannot move past eachother
10. A point about which something turns - a seesaw for example
11. Something that prevents the natural flow of a river