Learning Goal: To understand the relationship between force, impulse, and moment

Question

Learning Goal:

To understand the relationship between force, impulse, and momentum.

The effect of a net force ?F? acting on an object is related both to the force and to the total time the force acts on the object. The physical quantity impulse J? is a measure of both these effects. For a constant net force, the impulse is given by

J? =F? ?t.

The impulse is a vector pointing in the same direction as the force vector. The units of J? are N?s or kg?m/s.

Recall that when a net force acts on an object, the object will accelerate, causing a change in its velocity. Hence the object's momentum (p? =mv? ) will also change. The impulse-momentum theorem describes the effect that an impulse has on an object's motion:

?p? =J? =F? ?t.

So the change in momentum of an object equals the net impulse, that is, the net force multiplied by the time over which the force acts. A given change in momentum can result from a large force over a short time or a smaller force over a longer time.

In Parts A, B, C consider the following situation. In a baseball game the batter swings and gets a good solid hit. His swing applies a force of 12,000 N to the ball for a time of 0.70

Explanation / Answer

Note that

J (impulse) = F t

Thus, as F = 12000 N and t = 0.70E-3 s,

J = 8.4 Ns [ANSWER]

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