- #1

emilytm

## Homework Statement

As a 75.0 kg man steps onto a scale, the spring inside the scale compresses by 0.65 mm. Excited to see that he has lost 2.5 kg since his last weighing, he jumps 0.3 m straight up into the air and lands directly on the scale.

What is the spring’s maximum compression?

What reading, in kilograms, does the scale give when the spring is at its maximum compression?

## Homework Equations

U

_{s}=½k(Δl)

^{2}

## The Attempt at a Solution

I used U

_{s}=½k(Δl)

^{2}to find the spring constant, which I found to be 104.1N/m. Next, I found his total energy while he was jumping in the are, which was all in the form of gravitational potential energy. That was (9.8)(75kg)(.3m)=220.5J. That would also be equal to the kinetic energy of the man right before he makes contact with the scale after he jumps. I am not sure what to do next. Do I use the equation for elastic potential again to find the compression of the spring? I guess I don’t really know what maximum compression means. Thanks!

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