I have a question in regards to work and kinetic energy. The is #18 in Chapter 7

Question

I have a question in regards to work and kinetic energy. The is #18 in Chapter 7 of Physics for Scientists and Engineers 6th Edition by Mosca and Tipler. The actual question reads: (a) Estimate the work done on you by gravity as you take an elevator from the ground floor to the top of the Empire State Building, a building 102 stories high. (b) Estimate the amount of work the normal force of the floor did on you. Hint: The answer is not zero. (c) Estimate the average power of the force of gravity. I would really appreciate some help on this as soon as possible. Please show me step by step how to solve (a), (b), and (c) and how to get the answers with the correct formulas. That would help me out so much!

Explanation / Answer

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for part a>
w=FS(cosa)

F=mg(constant) where m is ur mass ang g is gravitational acceleration

S=hieght of empire state building

a=180degree since F is downwards and S is upwards

for part b>

apply work kinetic energy theorum

since only two forces are there gravity and normal

work done by gravity(calculated in a part)+work by normal=change in K.E. i.e=0 since u r initially and finally in rest

this gives work by normal = -ve(work by gravity)

for part c>

u need more data about the acceleration or velocity during journey as u need total time taken in journey, lets say its T

then power=work by gravity/T

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