How long would it take for a motor to raise a load into the air?

Question

The problem is asking to find how long it will take to raise the load into the air with the given information.
The information to solve the problem is as follows:

100 kilogram mass for the load
100 watts of power for the motor 
60% efficiency of the motor
5 meter for the height that the load is raised.
Time= ? seconds
 Explain why please. 

Thank you.

Answer

p = 60% x 100 w = 60 w = 60 kg*m2 s^&minus;3

f=ma =100 kg x 9.81 m/s^2 = 981 kg*m/s^2 (981 newtons)

w=fd = 981 kg-m/s^2 x 5m = 4905 kg*m^2/s^2

p = w/t = (4905 kg*m^2/s^2)/t = 60 watts = 60 kg*m^2 s^&minus;3

t = w/p  and you take it from there.

How long would it take for a motor to raise a load into the air?

Answers (1)