Science-conservation and dissipation of energy

Name 5 energy stores

Chemical, kinetic, gravitational potential, elastic potential, thermal

Name 4 ways energy can be transferred

Heating,waves,electric current,mechanically

What is a system?

An object or group of objects

What is a closed system?

A system where neither matter nor energy can enter or leave

What is work done?

energy transferred when a force moves an object

What is the unit for energy?

Joules (J)

What is one joule of work?

the work done when a force of 1N causes an object to move 1m in the direction of the force

Describe the energy transfer when a moving car slows down

energy is transferred mechanically from the kinetic store of the car to the thermal store of its brakes

Describe the energy transfer when an electric kettle is used to head water

The electric current in a kettle transfers energy to the heating element's thermal store

Describe the energy transfer when a ball is fired using an elastic band

energy is transferred mechanically from the elastic store of the elastic band to the kinetic store of the band

Describe the energy transfer when a battery powered toy car uses used

Energy is transferred electrically from the chemical store of the battery to the kinetic store of the toy car

Describe the energy transfer when a falling apple hits the ground

energy is transferred from the kinetic store of the apple and dissipated to the thermal store of the surroundings by sound waves

Name the unit that represents one joule transferred per second.

Watt (W)

A motor is 30% efficient. What does that mean?

30% of the energy is usefully transferred and 70% is dissipated