Question

A skier of mass 50 kg stands at A at the top of a ski jump. He takes off at A for his jump to B. Calculate the change in his gravitational potential energy between A and B.

Answer 1

Where is the height in ur question.. The question is with unmentioned quantity

Though it is not mentioned, bt as the question is known to me & i am familiar with the question and I have solved it many times so the answer will be :-
Given, m = 50 kg, h = 75 m, h = 60 m
At point A, PE = mgh = 50 x 10 x 75 = 37500 J
At point B, PE mgh = 50 x 10 X 60 = 30000 J
Change in PE = PE, -PE, = 37500- 30000 = 7500 J

Answer 2

Answer:

Change in the gravitational potential energy between A and B is $500(x-y) J$

Explanation:

Given the mass of skier, $m=50 kg$

         acceleration due to gravity, $g=10m/s^{2}$

         Let the height at A be $x$

            and height at at B be $y$

Then difference in the heights is $x-y$

Potential energy at height h from the ground is, $PE = mgh$

Potential energy at A from the ground is,

                            $PE= 50\times 10 \times x$

                                   $= 500x\ J$

Potential energy at B from the ground is,

                            $PE= 50\times 10 \times y$

                                   $= 500y\ J$

Change in the potential energy is

                         $\Delta PE=500x-500y$

                                  $=500(x-y) J$

Change in the gravitational potential energy is $500(x-y) J$.