iGCSE Energy Transfer

The Sankey diagram represents the energy transfer in a standard filament light bulb. Which arrow represents the useful energy?

• light energy arrow

• electrical energy arrow

• heat energy arrow

• all three arrows

What is the main energy transfer taking place in a car?

• chemical to kinetic

• electrical to chemical

• chemical to gravitational potential

• kinetic to electrical

The efficiency of a device can be calculated using the relationship between useful energy and supplied energy. Which equation represents the relationship between useful energy, supplied energy and efficiency?

• efficiency = useful energy/total energy supplied

• efficiency = total energy supplied/useful energy

• efficiency = useful energy × total energy supplied

• none of the above as they do not consider the wasted energy

Food is a store of energy. Which of the following types of energy store represents how energy is stored in food?

• thermal energy

• kinetic energy

• nuclear energy

• chemical energy

Using the equation for efficiency, what is the efficiency of the light bulb in question 5?

• 0.1

• 0.5

• 0.9

• 90

A rollercoaster stores 240 kJ of energy at the top of its run. The carriage has an efficiency of 0.35 when transferring gravitational energy to kinetic energy. What is the useful kinetic energy at the lowest point of the track?

• 688 kJ

• 1 kJ

• 100 J

• 84 kJ

A child’s slinky is stretched between two points. How is energy being stored in the spring?

• chemical energy

• elastic energy

• gravitational energy

• nuclear energy

Complete the sentence: The principle of conservation of energy states that

• energy can be created by burning chemical stores.

• energy cannot be created nor destroyed, only transferred from one form to another.

• once energy is used up it no longer exists.

• all energy is the same.

Looking at the difference in energy input to useful energy output in question 8, where has the wasted energy gone in the rollercoaster?

• Energy is transferred to the surrounding air as a consequence of air resistance.

• Energy is transferred to the tracks in the form of thermal energy due to friction between the carriage and the tracks.

• Energy is transferred to the air as sound from the noise the carriage makes going down the tracks.

• All of the above.

A cooker has an efficiency of 0.65. If the cooker transfers 10 000 kJ to cook a chicken, how much energy must have been supplied to the oven?

• 15 400 kJ

• 6500 kJ

• 650 J

• 1 kJ