Momentum Chapter 2 Section 3 Notes

Imagine This…  Imagine a smart car and a dump truck traveling with the same velocity. If both drivers applied the brakes at the same time, which vehicle will stop first?

Answer  You probably said the smart car would stop first but why?  We know smaller objects (objects with less mass) are easier to stop than larger object (objects with more mass)  Why is this? The answer is momentum.

Momentum  The momentum of an object depends on the object’s mass and velocity.  Simply put, the more momentum an object has, the harder it is to stop that object or change its direction.

Calculating Momentum  Momentum could be calculated using the following equation:  p=m*v where: p=momentum m=Mass (in Kg) v=Velocity (m/s) + direction So…what are the units for momentum?

Momentum Triangle p m v

Lets check out an example  What is the momentum of an ostrich with a mass of 120 kg that runs with a velocity of 16 m/s north?  p=m*v  p=120kg*16m/s north  p=19,200 kg*m/s north

The Law of Conservation of Momentum  States that anytime objects collide, the total amount of momentum stays the same.  This is true for any collision whether the objects stick together, or bounce off each other after they collide.  p total =p 1 +p 2 +p 3 …

Examples of Conservation of Momentum  When football players tackle another player, they stick together. The velocity of each player changes after the collision because of the conservation of momentum.  ouch... ouch...  When they stick to each other, their masses are added but their velocity’s are less.

Objects that bounce off each other  The transfer of momentum causes the objects to move in different directions at different speeds.  However, the total momentum of all the objects will remain the same before and after the collision.  momentum in space! momentum in space!