Rocket stares at the bike in the shop. "Go!" he tells it. The bike does not move.
Raven giggles. "What do you notice? Words do not move bikes."
Nova hovers over the handlebars. "Something has to act on the bike," she says. "What do your hands and feet do?"
Rocket thinks. "They push and pull things!" He opens his shop notebook.
A force is a push or a pull.
A force can make something change speed.
A force can make something change direction.
A force can even change the shape of something, like squeezing a sponge.
Every force has a size and a direction.
| Action | Push or pull? | What changes? |
|---|---|---|
| Feet press down on the pedals | push | the cranks start to spin |
| A grown-up walks a bike forward by the handlebars | push | the bike starts rolling |
| You tug a wagon handle | pull | the wagon starts moving |
| You squeeze a sponge | push | its shape changes |
| Statement | True or false? |
|---|---|
| A force is a push or a pull. | ? |
| A force can change the direction something moves. | ? |
| A force has no direction. | ? |
| A force can change the shape of an object. | ? |
Fantastic force hunting! Tomorrow we find out why some pushes make a bigger change than others.