# physics

a person jumps from a window 15m above a safety net. The survivor stretches the net 1.0 m before coming to rest. What was the average deceleration experienced by the person when they were slowed to rest by the net? I do know the answer is -150m/s2,but I don't know how the answer was found.

Find the velocity when the person hits the net, a free fall of 15 m.

Vfinal= sqrt (2gh) where g is the acceleration due to gravity, and h is the height.

Now the physics of the net.
The average velocity will be the initial velocity (above) divided by two. So the time it takes in the net is (time=1m/avgvelocity).

Finally,
avg deacceleration=change in velocity/time
= vabove/time=sqrt(2gh)/1m/avgvel)
= sqrt(2gh)vavg /1=sqrt(2gh)sqrt(2gh)/2
= gh

Neat question. Check my thinking.

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