# Physics Impulse

This is the problem I am dealing with: "One of the functions of an automotive air bag is that it lengthens the collision time. Without an air bag, suppose the 100Ns impulse of a collision is taken up by a fairly rigid dashboard, requiring a time of 15 ms. Find the amount of force exerted on the passenger."

Up till this problem I have only dealt with problems using the equation F x Change in Time = Mass x Change in Velocity. This problem only gives me 2 of the 4 variables in that equation, so I am at a loss of how to figure it out. Please help!

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remember the definition of impulse; this lets you continue. –  Arnold Neumaier Nov 18 '12 at 17:00

You're given the impulse and time, so simply susbtitute the given variables in the formula which calculates the impulse...

Which is

impulse = F * change in time


So... substitue the variables given to you and rearrange

100 = F * 15
F = 100 / 15

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