Answer:
t= 71.42 s
Explanation:
Given that
Power ,P = 100 Watt
Efficiency of the motor ,η = 70 %
mass , m = 100 kg
h = 5 m
Let's take time taken = t
The work done to move 100 kg by 5 m
W= m g h
W= 100 x 10 x 5 ( take g= 10 m/s²)
W = 5000 J
We know that 1 Watt= 1 J/s
Therefore
P x t= W
Now by putting the values in the above equation
100 x t x 0.7= 5000
[tex]t=\dfrac{5000}{70}\ s[/tex]
t= 71.42 s
Therefore the time taken by motor will be 71.42 s.
