Skip to content

A bigger push

Forces and motion · level 1, lesson 3 of 6

A question to start

You give a ball a little tap, and it rolls slowly. You give it a big kick, and it flies off. What is different?

The idea

A small push gets something moving slowly. A bigger push gets it moving faster. The size of a force is how hard it pushes or pulls: a tap is a small force, a kick is a big one.

A push that goes on for longer does more too. Push a friend on a swing for a moment, and they swing a little. Keep pushing all the way, and they swing higher.

a tap: slow, a short waya kick: fast, a long way

When we draw a force, we draw an arrow. The arrow points the way the force pushes, and a bigger force gets a longer arrow.

On Mars, a ball kicked as hard as on Earth starts just as fast. Then the weaker gravity lets it fly higher and farther before it lands.

Worked examples

1. A marble race. Flick one marble gently and another hard. The hard flick sends its marble faster and farther.

2. A swing. Little pushes give little swings. Bigger pushes, given at the right moment, give bigger swings.

Try it

  1. Which gets a ball moving faster: a tap or a kick?
  2. In a picture, how do we show a bigger force?
  3. You want a toy car to roll all the way across the room. Do you push it gently or hard?
  4. Would a ball kicked on Mars go farther or less far than on Earth?
Answers
  1. A kick.
  2. With a longer arrow.
  3. Harder.
  4. Farther: weaker gravity pulls it down more slowly.

Common mistake

"A bigger ball always needs a bigger push." A big beach ball is light and easy to push. It is how heavy something is, not how big it looks, that makes it hard to get moving. That is the next lesson.

Where it leads