Momentum and Circular Motion

Momentum

Newton’s first law states that an object stays at rest unless acted on by an external force.

Newton’s second law states that force is proportional to the rate of change of momentum, unless acted on by an external force.

Newton’s third law states that an action has an equal and opposite reaction.

The Principle of Conservation of Momentum - In a collision, the momentum before the collision is equal to the momentum after the collision, unless acted on by an external force.

The Principle of Conservation of Energy – The total energy after the change is always equal to the total energy before the change, unless acted by an external force.

Area under force-time graph is impulse/momentum.

An elastic collision is where kinetic energy is conserved, but most collisions are inelastic.

Linear momentum is the momentum in a straight line (p = mv).

Circular Motion

In circular motion, linear velocity is at tangents around a circle at any point.

Acceleration and force are directed towards the centre of the circle.

Angular velocity is the velocity around the circle.

An object changing velocity around the circle means that it is accelerating with a constant speed. This is because the direction is constantly changing.

Centripetal force and acceleration are towards the centre of the circle.

Centrifugal force is away from the centre of the circle.

1 radian is equal to 57.3 degrees.

©2011 Grant Dwyer