An elevator motor provides 45.0 kW of power while lifting an elevator 35.0 m. If the elevator contains seven passengers each with an average mass of 70.0 kg and it takes 20.0 s to accomplish this task

Question

a) Draw a diagram.

b) States the formulas and givens

c) Determine the mass of the elevator.

Answer 1

Power = Rate of doing work

P = W/time = 45 KW = 45*10³ J/s

work in this case is gain in Potential energy =

( m+ nM)g*h

45*10³ J/s = W/ time= ( m+ nM)g*h/time, Time =20Sec

Here m= Mass of elevator

M = mass of each person = 70 Kg

n= number of persons

45*10³ = ( m+ nM)g*h/20

Now plug in n = 7, M= 70 h= 35, g= 9.8m/s²

m= 2134 Kg