gravitational potential energy

what is energy in the gravitational store of an object is defined as?

The energy an object has due to its height in a gravitational field

If an object is lifted up…

energy is transferred to its gravitational potential store

If an object falls….

energy will be transferred away from its gravitational potential store

how can gravitational potential energy be calculated?

Ep = m × g × h

what does Ep represent?

Ep = gravitational potential energy, in joules (J)

what does m represent?

mass, in kilograms (kg)

what does g represent?

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

what does h represent?

h = height in metres (m)

so what is the word equation to calculate gravitational potential energy?

gravitational potential energy = mass x gravitational field strength x height

what is the gravitational field strength on Earth?

approximately 9.8 N/kg

what is the gravitational field strength on the moon in comparison to Earth? (2)

• The gravitational field strength on the surface of the Moonis less than on the Earth

• This means it would be easier to lift a mass on the Moon than on the Earth

what is the gravitational field strength on gas giants (Jupiter and saturn) in comparison to Earth?

• The gravitational field strength on the surface of the gas giants is more than on the Earth

• This means it would be harder to lift a mass on the gas giants than on the Earth

A man of mass 70 kg climbs a flight of stairs that is 3 m higher than the floor. Gravitational field strength is approximately 9.8 N/kg. Calculate the energy transferred to the man's gravitational potential energy store.

Step 1: List the known quantities

• Mass of the man, m = 70 kg

• Gravitational field strength, g = 9.8 N/kg

• Height, Δh = 3 m

Step 2: Write down the equation for gravitational potential energy

ΔEP = mgΔh

Step 3: Calculate the gravitational potential energy

ΔEP = 70 × 9.8 × 3 = 2058 J