IGCSE Energy Transfer (Year 9)

Which of the following is NOT a store of energy?

• Kinetic

• Gravitational

• Elastic

• Thermal

• Sound

Which of the following is NOT a transfer of energy?

• Heat

• Kinetic

• Mechanical

• Electrical

• Waves

Which of the following gives the best description of the energy transfers that occur when a ball has been thrown vertically upwards?

• Energy is transferred from the kinetic energy store of the ball to its gravitational potential energy store. Energy is also transferred from the kinetic energy store to the thermal energy store of the ball and the air as work is done by air resistance to slow it down.

• Energy is transferred from the gravitational potential energy store of the ball to its kinetic energy store. Energy is also transferred from the gravitational potential energy store to the thermal energy store of the ball and the air as work is done by air resistance to slow it down.

• Energy is transferred from the kinetic energy store of the ball to its gravitational potential energy store. Energy is also transferred from the thermal energy store of the ball to the thermal energy store of the air as work is done by air resistance to slow it down.

• Energy is transferred from the gravitational potential energy store of the ball to its kinetic energy store. Energy is also transferred from the thermal energy store of the ball to the thermal energy store of the air as work is done by air resistance to slow it down.

An electric motor transfers 24 J of energy usefully, but wastes 16 J of energy in doing so. What is the efficiency of the motor?

• 16 J ÷ 24 J = 0.67

• 24 J ÷ 16 J = 1.5

• 16 J ÷ 40 J = 0.4

• 24 J ÷ 40 J = 0.6

What would an efficiency of 0% tell you about the energy transfers of a device?

• The device is not working.

• The device is not working in the way that it was designed.

• There is not enough energy being transferred for the device to work.

• All the energy that is transferred is to an unwanted energy store.

If the speed of an object is increasing, which energy store increases?

• kinetic

• gravitational

• elastic

• thermal

As an object falls its store of kinetic energy increases and which store of energy decreases?

• gravitational

• thermal

• elastic

• nuclear

Which kettle would cool down faster?

• Black surface

• Shiny surface

How is energy from the sun transferred to Earth?

• Conduction

• Convection

• Radiation

• Evaporation

Select THREE reasons why the ice does not melt

• Thermal energy transfer by CONDUCTION is reduced because water is a poor conductor.

• Thermal energy transfer by CONDUCTION is reduced because glass is a poor conductor.

• Thermal energy transfer by CONDUCTION is reduced because water is a good conductor.

• Thermal energy transfer by CONVECTION is reduced because hot water is LESS dense than cold water and so no convection current is set up.

• Thermal energy transfer by CONVECTION is reduced because hot water is MORE dense than cold water and so no convection current is set up.