Question

Use the formula GPE =mass x gravity x heigth To calculate the gracitational potential energy (GPE) of the bag of sugar before it falls from the table. (Assume g = 10N/Kg)

Answer 1

Explanation:

When an object is lifted in a gravitational field, energy is transferred to a gravity store. This store is called gravitational potential energy.

gravitational potential energy = mass × height × gravitational field strength (g)

This is when:

gravitational potential energy is measured in joules (J)

mass is measured in kilograms (kg)

height is measured in metres (m)

gravitational field strength (g) is measured in newtons per kilogram (N/kg)

Example

Calculate the energy transferred to the gravity store when a woman of mass 60 kg climbs 4 rungs up a ladder. Each rung is 15 cm high.

First calculate the distance climbed in metres:

15 cm is 0.15 m

0.15 × 4 = 0.6 m

Then calculate the gravity store increase (the gravitational potential energy), remembering that g is 10 N/kg on Earth:

gravitational potential energy = mass × height × gravitational field strength (g)

gravitational potential energy = 60 × 0.6 × 10

gravitational potential energy = 360 J