Year 8 Physics Quiz

The equation for Energy Efficiency is:

• (useful energy/wasted energy) x 100

• (wasted energy/useful energy) x100

• (useful energy/total energy) x100

• (total energy/useful energy) x100

A petrol engine takes 1000J of chemical energy and does 250J of work. What is it's efficiency?

• 75%

• 25%

• 50%

• 20%

An electric motor uses 50J of electrical energy and does 40J of work. What is it's efficiency?

• 20%

• 15%

• 60%

• 80%

A cyclist has 200J of energy and does 30J of work. What is their efficiency?

• 15%

• 20%

• 75%

• 10%

A rocket engine takes in 800J of chemical energy and changes this into 480J of kinetic energy and 320J of heat energy. What is it's efficiency?

• 55%

• 40%

• 60%

• 90%

A TV takes in 600J of electrical energy and gives out 300J of light, 240J of sound and 60J of heat energy. What is it's efficiency?

• 90%

• 80%

• 50%

• 20%

Energy Efficiency is measured in:

• Joules (J)

• Meters per second

• Percentage (%)

• J/ml/C

Energy efficiency is:

• a measure of how much total energy is wasted.

• a measure of how much input energy is converted into useful output energy (in %).

• a measure of how much input energy is converted into useful output energy (in Joules).

• a measure of the total output energy as a ratio of total input energy.

The flow diagram above is for a fluorescent light bulb. What's it's efficiency?

• 53.33%

• 76.33%

• 37.21%

• 47.66%

The above flow diagram is for a kitchen blender. What's it's efficiency?

• 30%

• 40%

• 50%

• 90%