Impulse Force

Question:

In a case where the force of impulse is changing, how will it change with respect to time? Is there any graph to show its changes?

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Answer:

An impulse force is defined as a force applied for a short time, compared to the time of observation of the system. Normally we think of impulsive forces as those arising from a collision as a bat striking a ball. Such a force does change with respect to time.

As the two objects, the bat and the ball, make initial contact the forces between the individual atoms of bat and the ball displace the atoms from their normal position, flattening each object slightly. As the objects flatten, more and more atoms become involved in the contact so the total force between the bat and the ball increases sharply. The change in momentum of both objects is given by the product of the force applied times the time of contact. When the momentum of the ball has been changed enough to reverse its velocity the contact is broken and the ball flies away from the bat.

The details of how the force varies with time are quite complicated. Normally we can not calculate it. It is possible to measure it with some elaborate experiments. In that case an accurate graph may be produced. For most purposes it is sufficient to estimate how the force of impulse varies with time. We know that is starts small, passes through a peak and becomes small again. Any graph that reflects these conditions will be a fair approximation of an impulsive force.

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