Solve Work-Energy Problem for Girl Cliff Diving

AI Thread Summary
A girl jumps from an 80-meter cliff, and her mass is 64 kg. To ensure she does not sustain injuries, the minimum depth she must dive into the water is calculated to be 4.65 meters, given that her body can withstand a force of 11,000 N. If she dives 3.8 meters underwater, the force experienced by her body is approximately 13,473 N. It is noted that this calculation assumes a constant force in the water, which may not reflect real-life conditions. Understanding these dynamics is crucial for safety in cliff diving scenarios.
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Homework Statement


A girl is cliff diving. She jumps (assume from rest) from an 80 meter high cliff.

a) If her mass is 64 kg, and her body can only withstand a force of 11,000 N without breaking a bone, what is the minimum depth she must go into the water and not get hurt?

b) If we assume she goes 3.8 meters under the water, what force does her body feel?

Homework Equations


mgh+Fdcos(theta)=1/2mv2f

m = 64kg, vf = 0m/s F1 = 11000N, h = 80m, d2 = 3.8m, d1 = ?, F2 = ?

The Attempt at a Solution


a) I used the above equation to solve for d2 and I got an answer of 4.65m as the depth.

b) I used the above equation to solve for F2 and I got an answer of 13,473N as the force.
 
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That all looks right. But note the question assumes the force is constant in the water. That would not be true in practice.
 

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