Physics GCSE - Energy Topic

To calculate the elastic potential energy you must use the equation: E_e = 0.5 x spring constant x extension². (Extension must be in metres, m) Calculate the elastic potential energy stored in a spring with a spring constant of 200 N/m that has been stretched from a length of 117 cm to a length of 127 cm.

• 0.1 J

• 1.0 J

• 10.0 J

• 100.0 J

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.

As an object falls it gains kinetic energy as its _______________ ___________ energy store decreases.

Which is the correct equation that links work done, power and time?

• power = work done x time

• time = power x work done

• work done = power x time

• work done = power / time

If the speed of an object is increasing, its ____________ energy store is increasing.

To calculate the gravitational potential energy of an object you must use the equation: Ep = mass x gravitational field strength x height. Which of the following objects has the most gravitational potential energy?

• A 3 kg mass, 5 m above the ground on Earth (g = 9.8 N/kg)

• A 4 kg mass, 4 m above the ground on Venus (g = 8.9 N/kg)

• A 10 kg mass, 5 m above the ground on Mars (g = 3.4 N/kg)

• A 9 kg mass, 11 m above the ground on the Moon (g = 1.6 N/kg)

To calculate the kinetic energy of an object you must use this equation: E_k = 0.5 x mass x speed². Which of the following objects has the most kinetic energy?

• A 10 kg mass with a speed of 5 m/s.

• A 5 kg mass with a speed of 10 m/s.

• A 2 kg mass with a speed of 20 m/s.

• A 0.1 kg mass with a speed of 100 m/s.

Which of the following is NOT a transfer of energy?

• Heating

• Kinetically

• Mechanically

• Electrically

• Waves