Internal energy

Question 1

What is internal energy?

Answer 1

The sum of the randomly distributed kinetic and potential energies of atoms or molecules within the substance.

Question 2

How can you increase the internal energy of a body?

Answer 2

• Increasing temperature: Average KE will increase therefore internal energy increases
• Change phase: Electrostatic potential energy increases significantly

Question 3

What is the electrostatic potential energy in a Gas and why?

Answer 3

Zero because there are negligible electrical forces between atoms or molecules.

Question 4

What is the electrostatic potential energy in a Liquid and why?

Answer 4

Negative because energy needs to be supplied to break the atomic or molecular bonds.

Question 5

What is the electrostatic potential energy in a Solid and why?

Answer 5

Large negative value because electrostatic forces are very large.