Energy Stores

Question 1

Name three different energy stores

Answer 1

You could have named any three from the following: thermal, kinetic, gravitational potential, elastic potential, chemical, magnetic, electrostatic and nuclear.

Question 2

When an object slows down, which stores is energy being transferred away from?

Answer 2

The object’s kinetic energy store

Question 3

True or false? If the speed of an object doubles, the energy in its kinetic energy store also doubles

Answer 3

False
If the speed doubles the energy in the kinetic energy store quadruples because of the v^2 in the KE = 1/2 x m x v^2 formula

Question 4

A 2 kg block and a 5 kg block are both lifted to the same height. Which block has more energy in its gravitational potential energy store?

Answer 4

The 5kg block has more energy in its gravitational potential energy (GPE) store. It has a higher mass and the amount of energy transferred to a GPE store during lifting depends on mass, as Δ GPE = m x g x Δ h

Question 5

A melon with a mass of 1 kg is dropped from a height of 7m. Calculate the energy transferred from its gravitational potential energy store. The gravitational field strength is 10N/kg

Answer 5

70 J

Δ GPE = m x g x Δ h = 1 x 10 x 7 = 70 J

Question 6

An ostrich of mass 100 kg is running at 20 m/s. Calculate the energy in its kinetic energy store

Answer 6

20000J

KE = 1/2 x m x v^2 = 1/2 x 100 x 20^2 = 20000J