physics help on the last two please?

Question

A 0.60 kg basketball is dropped out of the window that is 6.2 m above the ground. The ball is caught by a person whose hands are 1.8 m above the ground. How much work is done by the ball by its weight?
25.872 J
What is the gravitational potential energy of the basketball, relative to the ground when it is released?
36.456 J
What is the gravitational potential energy of the basketball when it is caught?
J
How is the change (PEf - PE0) in the ball's gravitational potential energy related to the work done by its weight?

Answer 1

Hi Big T:

When caught, the will be PE=mgh, where h is 1.8 m. This will also be the difference between the energy at release and the Work done by the ball.

PE=mgh=.6*9.8*1.8=10.584 J

Lets compare with PE at window less Work done

PEwindow= 36.456 J
Work= 25.872 J
PEwin-Work=36.456-25.872=10.584 J
The numbers are identical.
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I am not sure what "PE0" or "PEf" are, the the work done by the weight is always equal to the loss in gravitational potential. I.e., if the work done is 20 J, then the gravitational potential must be -20 J lower.