Inertia

Motion doesn’t need a push

An interactive lesson with 7 steps, about 6 minutes: you predict, drag and solve, with instant feedback on every answer. It runs in your browser and needs JavaScript.

What you’ll learn

• An object’s velocity changes only when a net force acts on it (the first law).
• Moving at a constant velocity needs no net force. Friction is what usually stops things.
• Zero net force means constant speed AND constant direction.

Steps

1. The endless rink
2. Push, then let go
3. Galileo’s ramps
4. Newton’s first law
5. Engines off
6. Sudden stop
7. Balanced or not?