Problem 7.43 Part A A new record for running the stairs of the Empire State Buil
ID: 1771452 • Letter: P
Question
Problem 7.43 Part A A new record for running the stairs of the Empire State Building was set on February 3, 2003. The 86 flights, with a total of 1576 steps, was run in 9 minutes and 33 seconds If the height gain of each step was 0.20 m, and the mass of the runner was 69 kg, what was his average power output during the climb? Give your answer in both watts and horsepower. Express your answer using two significant figures Submit My Answers Give Up Part B Express your answer using two significant figures P= hp Submit My Answers Give Up Provide Feedback ContinueExplanation / Answer
Power can be calculated as energy used per unit time, that is change in P.E(=m*g*h) per unit time.
(A) Total vertical height of the stairs,h= 1576*0.2 = 315.2 m
value of g=9.8 m/s2, mass of runner= 69 kg
change in P.E= m*g*h=69*9.8*315.2= 213138.24 J
power = Energy/ time
time= 9 min 33 sec= (9*60)sec+33 sec= 540+33 sec= 573 sec
Power = 213138.24/573 Watts= 371.97 Watts
(B) 1 Hp=745.7 watts
hence, 371.97 watts = 371.97/745.7 Hp= 0.50 Hp