Force: Internal Energy

Question 1

What is internal energy?

Answer 1

• Energy stored in a system by the particles.
• ## Total kinetic energy and potential energy of all the particles that make up a system

Question 2

What is internal energy during changes of states?

Answer 2

1) Heating a Solid: Increases internal energy. Solid can turn into a liquid.
2) Heating up Liquid: Increases internal energy at some point liquid turns into a gas.
3) Cooling down Gas: Reduces internal energy and at some point gas condenses.
4) Cooling down liquid: Reduces internal energy and and eventually the liquid will freeze into a solid.

Question 3

What is sublimation?

Answer 3

• Solid can turn directly into a gas.

Question 4

Is mass conserved during changes of states?

Answer 4

Yes.

• Physical changes not chemical changes.
• Reverse the change, material recovers original properties.