Physics - 1 Conservation and Dissipation of Energy - 1.1 Changes in Energy Stores & 1.2 Conservation of Energy & 1.3 Energy and Work

How many energy stores are there?

8

What are the 8 energy stores?

- magnetic
- thermal
- chemical
- kinetic
- electrostatic
- elastic potential
- gravitational potential
- nuclear

How many energy transfers are there?

4

What are the 4 energy transfers?

- mechanical work
- electrical work
- heating
- radiation

Sankey diagram

Represents useful and wasted energy with arrows

What is the law of conservation of energy?

energy cannot be created or destroyed, only transferred

Work

applied force that causes an object to move

'Work done' is another way of saying...

energy transferred

Equation for work done:

work done = force x distance

What is work measured in?

J (or Nm)

Where does work done to overcome friction mostly go?

into thermal energy stores via heating

What does friction do?

oppose motion

Why do brakes work?

- friction opposes the motion of the wheel
- the kinetic energy of the wheels and vehicle is transferred by heating to the thermal stores of the brakes and the wheels