A 175lb person runs to a football stadium, up 90 rows of steps (each 20cm high)

Question

A 175lb person runs to a football stadium, up 90 rows of steps (each 20cm high) in 35 seconds. The student then drops a 2kg book off the stadium.

1.) What is the amount of work needed to reach the top of the stadium (for the weight of the person only, not including the 2kg book)?
2.) What is the power generated running to the top of the stadium (again, only for the person)?
3.) What is the potential energy of the person at the top of the stadium?
4.) What is the maximum potential energy of the book (assume it lands on level ground)?
5.) What is the impact velocity of the book?

I have answers of:
1.) W = 14047 J
2.) P = 401.3 watts
3.) PE = 14047 J
4.) PE MAX = 132 J
5.) v = 11.5 m/s

How do I get these answers? The more detailed the answer, I would truly appreciate it.
Thank you very much.

Explanation / Answer

Weight of person W = 175 lb                                 = 175 x 4.458 N                                 = 780.15 N Height of each row h = 20 cm                                  = 0.2 m Height of 90 rows H = 90 h                                 = 18 m Mass of book m = 2 kg Time t = 35 s 1.) The amount of work needed to reach the top of the stadium W ' = WH                                                                                                       = 14042.7 J 2.) The power generated running to the top of the stadium P = W ' / t                                                                                            = 401.22 watts
3.) The potential energy of the person at the top of the stadium U = WH                                                                                                    = 14042.7 J
4.)The maximum potential energy of the book U ' = mgH                                                                            = 352.8 J 5.) The impact velocity of the book v = [ 2gH ]                                                          = 18.78 m / s

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