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What happens when things collide

Ask questions and predict outcomes about the changes in energy that occur when objects collide

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What a learner can do afterwards

  • Predict the outcome of a collision based on the speeds and sizes of the objects
  • Explain that energy transfers from one object to another during a collision
  • Describe observable changes: one object speeds up, the other slows down, sound is produced

The lesson

You already know a fast-moving thing has more energy than a slow one. When two things bump into each other, some of that energy moves from one object into the other. That is called a collision.

Ball Abefore8Ball Aafter2Ball Bbefore0Ball Bafter6
Ball A was fast and hit Ball B, which was standing still. After the hit, Ball A slowed down and Ball B sped up.
Try it together

Mia rolls a fast toy car toward a car that is standing still. When they crash, the fast car slows down and the still car shoots forward. Some of the fast car's energy moved into the other car.

Good to know

Watch closely during a collision. You will often hear a sound, since some energy turns into sound instead of staying as motion. The size and speed of each object change what happens next.

In a collision, energy moves from one object to another: one usually slows down while the other speeds up, and you might hear a sound.

Watch it

Where it sits

Learn first

This opens up

Nothing builds on it yet.

Where this leads

Jobs that lean on this skill. Follow one to see everything it is built on.

Then practise

8 questions wait behind this lesson, each with its answer explained. Every answer feeds the sky: stars light as they are learned, and dim when it is time to come back.

What happens when things collide · Science, ages 9 to 10 · LightMySky