# In a Flash

Gravitational energy is used to propel the ride along the tracks.

## Gravitational energy

As you may have guessed, gravitational energy is energy associated with gravity. It is the potential energy stored by an object because of its higher position compared to a lower position. (e.g. if it's further away or closer to the ground).

Gravitational energy is energy associated with gravity.

# Burning Questions

## What is gravity?

Gravity is a force which tries to pull two objects toward each other. Earth's gravity is what keeps you on the ground and what causes objects to fall.

The Earth has gravity. Gravity holds everything close to this planet. Trees, water, animals, buildings, and the air we breathe are all held here by gravity. The planets, their moons, and the stars in the universe have gravity. Even our own bodies have gravity. The Earth's gravity is far stronger than our own so we don't notice the gravity our bodies have.

The Earth's tides are caused by the moon's gravitational pull on the oceans. Tides are the rise and fall of the ocean level as related to the shoreline.

## What causes gravitational energy?

Systems can increase gravitational energy as mass moves away from the centre of the Earth or other objects that are large enough to produce significant amounts of gravity (like our Sun, the planets and stars).

## What is gravitational energy?

Gravitational energy is the energy stored in an object due to its height above the Earth (e.g. if it's further away or closer to the ground). It is a form of potential energy.

An object's height above the ground gives it gravitational energy.

## What is an example of gravitational energy in action?

The pendulum is a simple machine for transferring gravitational potential energy to kinetic energy, and back again. When the bob is at the highest point of its swing, it has no kinetic energy, but its gravitational potential energy is at a maximum. As the bob swings downwards, gravitational potential energy is transferred to kinetic energy, and the bob accelerates.

At the bottom of its swing, the bob's kinetic energy is at a maximum and its gravitational potential energy is at a minimum.

As the bob swings upwards, its kinetic energy is transferred to gravitational potential energy again. At the top of its swing, it once again has no kinetic energy, but its gravitational potential energy is at a maximum.

Note that the bob's swing will become lower with each swing, because some energy is also transferred as heat to the surroundings.

Further examples are:
Water stored in a dam, a large boulder at the edge of a cliff, roller coasters, a skateboard on the top of a ramp.

A pendulum converts potential energy from gravity into kinetic energy and back again.

# What Do You Mean?

Gravitational force pulls the ball back towards the ground.

Gravitational energy is potential energy stored in an object based on its distance from the Earth.

Potential energy is energy that is stored in an object or substance. Gravitational energy is a form of potential energy.

The Earth, the Sun, planets and stars all produce significant amounts of gravity.

# Cool Facts

When you ride on a rollercoaster, you might experience 'microgravity', which means you are falling at the same speed as the vehicle you're travelling in.

# Cool Facts

Black holes have the strongest gravitational pull in the entire Universe.

# Speedy Summary

The amount of gravitational potential energy is dependent upon the mass (m) of the object and the height (h) of the object.

Gravitational energy is stored potential energy in an object based on its high position compared to a lower position.

# Teacher's Toolkit

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