Q-files is free to read thanks to advertising. To enjoy the site completely ad-free, please subscribe. Learn more →

About Q-files Contact Us Menu
Advertisement

EASY READ Science

What causes motion?

Motion is any kind of movement. Motion is caused by forces. A stationary object does not move unless a force acts on it to start it going. Once it is moving, it carries on at the same speed and in the same direction unless a force makes it speed up, change direction or slow down and stop.

A space probe travels past Jupiter
A space probe travels past Jupiter

Different types of motion

Different types of motion at a playground
Different types of motion at a playground

This illustration shows examples of a number of different types of motion: linear motion (the football and slide), oscillating motion (the swing) and rotary motion (the bicycle wheels and roundabout).

The movement of a bus, demonstrating inertia
The movement of a bus, demonstrating inertia

Inertia

In the illustration above, a boy is being thrown off his skateboard. The board stopped suddenly when it hit a rock, but the boy himself continued to move forwards. This was because of inertia: the tendency for objects that are moving to carry on moving. The heavier or faster the object, the greater its inertia.

Advertisement

If a bus stops suddenly, people on it fall forwards because there is nothing to stop them moving (although seat belts would hold them in place). This is another example of inertia.

Consultant: Mike Goldsmith

Ready to find out more?

Here are some pages in other parts of Q-files you might like to explore:

Forces
Motion
Advertisement

pics

The Juno space probe travels past Jupiter. A space probe is an unmanned spacecraft. Once it is launched from Earth it needs no force to propel it across space. It carries on at the same speed and in the same direction, because there is no force (in this case, air resistance) to slow it down.
Different types of motion at a playground
The forward movement (top) and braking (above) of a bus demonstrates inertia.

Without in any way limiting Q-files Ltd’s exclusive rights under copyright, any use of this publication to “train” generative artificial intelligence (AI) technologies to generate text is expressly prohibited. Q-files Ltd reserves all rights to license use of this work for generative AI training and development of machine learning language models.