Momentum and Kinetic Energy

How can we describe the motion of a car?

We have already described its momentum as

p = m v

Now we can describe its Kinetic Energy as


KE = (1/2) m v2

Momentum, p = m v, and Kinetic Energy, KE = (1/2) m v2, both describe the motion of an object. Both depend upon the object's mass and speed. However, Momentum and Kinetic Energy are not the same thing.

Momentum is a vector. The total momentum of a system could be zero even tho' individual parts have momentum.

Kinetic Energy is a scalar. Nothing "cancels it out". Energy can be changed from one form to another (including heat!).

Free Fall


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(C) 2003, Doug Davis; all rights reserved