Momentum, collision and impulse comprehensive notes

MOMENTUM & IMPULSE

Momentum

 The product of an object’s mass and its velocity
 p=mv
 Measured in kgms-1
 Vector (direction same as direction of velocity)
 Directly proportional to velocity

Change in momentum
 p = mv
 Change in momentum is in the same direction as the force causing
the change
 If the Fnet acting on the object = 0, there is no change in
momentum

Newton’s 2nd Law of Motion in terms of Momentum
 The resultant force acting on an object is equal to the rate of
change of momentum of the object in the direction of the resultant
force
 Fnet = p∆t

Conservation of Momentum
 The total linear momentum of a closed system remains constant
 Isolated system a system free from the influence of a net external
force (law only applies to isolated systems)
 Total momentum before collision = total momentum after collision
 mAvAi+mBvBi= mAvAf+mBvBf where f = after the collision and i = before
the collision
 Must choose a + direction when applying law




Collisions

 There are 3 types of collisions:
1. Start with 2 objects and end with 2
2. Start with 1 object and end with 2 (explosion)
3. Start with 2 objects and end with 1
 Momentum is always conserved in collisions
 Kinetic Energy isn’t always conserved- objects deform (give off
light, produce sound, heat up, change shape)