# Air Resistance of a Diver using Ek and Eg

**1. The problem statement, all variables and given/known data**

A 57.0 kg diver dives from a height of 15.0 m. She reaches a speed of 14.0 m/s just before entering the water. What was the average force of air resistance (e.g., friction) acting on the diver?

What is the force of friction underwater if she reaches a depth of 2.5 m before stopping? Do not neglect the buoyant force of 500 N acting on the diver once underwater

**2. Relevant equations**

Eg=mgh

Ek=(1/2)mv^2

Et=Ek+Eg

W=Ef-Ei

W=change in Ek

W=fd

**3. The attempt at a solution**

Ek=(1/2)(57kg)(14m/s)^2

=5586J

W=Ek

=5586J-0J

W=fd

5586J=F(15m)

5586/15=F

F=372.4N

Fnet=ma

=(57kg)(9.8N/kg)

=558.6N

Fnet=558.6N

Fapp-Ff=558.6N

372.4N-Ff=558.6N

Ff=186.2N

I’m not sure if I solved for friction properly. The way that I solved here doesn’t work for the next step in the water, so I think initially started wrong.

http://ift.tt/1fsh3An

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