How Does the Work-Kinetic Energy Theorem Apply to a Diving Scenario?

[master_333]

Homework Statement

A high diver(m = 62kg) walks off a platform 15 meters above the water below (assume velocity inital = 0). The diver reaches a depth of 2.2 metres in the pool before coming to a stop.
1. What is the diver's change in kinetic energy (Answer: -9114J)
2. What is the average force of the water pushing up on her? (Answer: 4750 N ... the acceleration corresponds to a about 8 g's)

I don't get the correct answer to the first question and I don' know how to attempt the second question. Please help and please show me the steps.

Homework Equations

Work Energy Theorem

The Attempt at a Solution

1. Change in GPE = Change in KE
mgh = change in KE
(62kg)(9.8)(17.2m(
change in KE = 10450.72, which is the wrong answer.

 

[Doc Al]

1. What is the diver's change in kinetic energy

I presume they want the change in KE once she hits the water. So what is her KE when she hits the water?

 

[master_333]

I presume they want the change in KE once she hits the water. So what is her KE when she hits the water?

The KE when she hits the water is 9114J

 

[Doc Al]

The KE when she hits the water is 9114J

There you go. So you can answer part 1 now, correct?

 

[master_333]

How do I sart part 2

 

[master_333]

How do I sart part 2

Sorry, How do I start part 2

 

[Doc Al]

Sorry, How do I start part 2

By applying the work energy theorem.

Remember, you are trying to find the average force that the water exerts. What other force acts?