Conservation of Momentum

v1i

m1 m2

v2i

m1 m2

F1 F2v1f v2f

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• For an isolated system, the law of conservation of momentum can be stated as follows:

The total momentum of all objects interacting with one another remains constant regardless of the nature of the forces between the objects.

Faysal`s momentum is 60 kg.m/s

mearth = 6x1024 kg Vearth=?

• Principle of conservation of momentum doesn`t apply only to collisions.

When the skaters stand facing each other, both skaters have zero momentum, so the total momentum of both skaters is zero.

When the skaters push away from each other, their momentum is equal but opposite, so the total momentum is still zero.

Both begin at rest, so the total initial momentum is zero. When the hammer hits the ball, it gives momentum to the ball. Thus, the total momentum will be kept at zero.

Example:

• A 76 kg boater, initially at rest in a stationary 45 kg boat, steps out of the boat and onto the dock. If the boater moves out of the boat with a velocity of 2.5 m/s to the right,what is the final velocity of the boat?