MOMENTUM AS A VECTOR
 

Suppose that the speed of an object (in meters per second) is v, and that the mass of the object (in kilograms) is m. Then the magnitude of the momentum p is their product:
p = mv
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This is not the whole story. To fully describe momentum, the direction as well as the magnitude must be defined. This means that we must consider the velocity of the mass in terms of its speed and direction. (A 2-kg brick flying through your east window is not the same as a 2-kg brick flying through your north window.) If we let v represent the velocity vector and p represent the momentum vector, then we can say
p = mv