
Force
 needed to change the velocity of an object
 rate of change of momentum

Momentum
 mass x an objects velocity
 units: kgms^{1}
 vector quantity
 p=mv

Newton's Laws of Motion
 First: an object remains at rest or in uniform motion unless acted on by a force
 Second: the rate of change of momentum of an object is proportional to the resultant force on it
 Third: when objects interact they exert equal and opposite forces on each other


Forcetime graphs
 the area under the line of a forcetime graph represents the change of momentum or the impulse of the force

Principle of Conservation of Momentum
 For a system of interacting objects, the total momentum remains constant, provided no external forces acts on the system
 m_{B}v_{B} + m_{A}v_{A} = m_{A}u_{A} + m_{B}u_{B}
 (m_{B} + m_{A})V = m_{A}u_{A} + m_{B}u_{B}

Elastic and Inelastic Collisions
 Elastic: one where there is no loss of kinetic energy, e.g. bouncy ball
 Totally Inelastic: one where the colliding objects stick together, e.g. car crash
 Partially Inelastic: one where the colliding objects move apart and have less kinetic energy after the collision than before

Explosions
 m_{B}v_{B }= m_{A}v_{A}
 move apart in opposite directions

