Angular Velocity
Forces and Motion

Key Drop

Enrichment Activity for 5-11 11-14

What you need

  • A bunch of about 3 keys
  • A large paperclip or washer
  • A pencil
  • 1m of string


  1. Tie the bunch of keys to one end of the string and the paperclip to the other
  2. Place the string over the pencil so that the keys hang down a couple of centimetres
  3. Hold the paperclip horizontally out to the other side
  4. Let go of the paperclip

Results and Explanation

The paperclip winds around the pencil and stops the keys hitting the floor!
This is because the keys pull the paperclip towards the pencil, but gravity is also pulling it downwards so it moves in a circle. As the paperclip gets closer to the pencil, its angular velocity increases, and it wraps around the pencil.

Angular Velocity
is a special case of Velocity
IOP DOMAINS Physics CPD programme

Electricity CPD videos

Our new set of videos gives teachers and coaches of physics a preview of the training we offer ahead of this term's live support sessions.

Find out more