What does a force actually do? A push or a pull can change three things:

• Speed — make something go faster or slower (or start and stop).
• Direction — bend its path, or send it a new way.
• Shape — squash, stretch, bend or twist it.

Press play and watch a ball get a push that speeds it up — then another that turns it.

Forces change shape, too. Press harder and harder on this ball and watch it squash flatter — the bigger the arrows, the bigger the squash.