⇒ In collisions between two or more bodies, both momentum and energy are conserved

⇒ However, the total kinetic energy of the bodies does not always stay the same because the kinetic energy can be transferred to other types of energy

⇒ Colllisions in which the kinetic energy of the particles is the same after the collision as it was before are described as elastic

⇒ Collisions in which kinetic energy is transferred to other forms of energy are described as inelastic

⇒ Most collisions on a large scale are inelastic, but collisions between atomic particles are often elastic

⇒ Although momentum and kinetic energy are very different quantities, they are linked by some useful equations.

⇒ It is important to remember that momentum is a vector quantity and kinetic energy is a scalar quantity

• We give momentum a direction: for example, +p to the right and -p to the left
• A vehicle travelling with momentum p has as much kinetic energy when travelling to the right as it does to the left

⇒ When a vector is squared, it becomes a scalar quantity

⇒ Also see our notes on:

• Introducing Momentum
• Momentum and Impulse
• Conservation of Linear Momentum
• Elastic and Inelastic Collisions