Inertia (WJEC GCSE Physics)

• The concept of inertia is closely related to motion, it is defined as:

The resistance of an object to a change in its state of motion or rest

• This means that 
  • If an object is at rest, it will tend to remain at rest
  • If an object is moving at a constant velocity (constant speed in a straight line), it will continue to do so
• The inertia of an object is related to its mass:
  • The greater the mass an object has then the greater its inertia
  • So a greater resultant force will be required to change its motion

Demonstrating Inertia

Removing the card causes the coin to fall into the glass. The inertia of the coin maintains its state of rest and its weight pulls it into the water.