Average Force in a Collision

## Question:

Ft=mv-mu , where the force F is the AVERAGE FORCE. What is the meaning of that AVERAGE? Is there any graph to show it physical meaning?

Thanks very much for answering the questions!!!

## Answer:

Because an impulsive force is over so quickly knowing the details of how an impulsive force varies with time is difficult. We frequently deal with the average force. Newton's second law may be stated in terms of changes in momentum in that the force is the rate of change of momentum. The average force during an impulse is that force which would produce the same change in momentum as the actual force. If we are willing to assign the average force to the whole time interval of the impulse, this becomes F=(change in momentum) divided by (change in time). Or F times the (change in time)=(change in momentum). Which is the formula you have in your question.

The connection between the graph of the actual impulsive force with respect to time and that of the average force with resect to time is that the area under both graphs is equal. The actual impulse graph will be some sort of peak looking thing, the average force graph will be a square wave, flat on top.

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