Question

An electric motor raises a load of 0.2 kg, at a constant speed, through a vertical distance of 3.0 m in 2 s. If the acceleration of free fall is 10 m/s², the power in W developed by the motor in raising the load is :

Options

• 0.3

• 1.2

• 3.0

• 6.0

Answer 1

Mass of the load (m₁) = 0.2 kg
Height (h) = 3 m
Acceleration due to gravity (g) =10 m/s²
Time taken  (t) = 2s
We can calculate the work done against gravity as,
 Work done by the car = (Weight of body) (Vertical distance)
                                    = (0.2)(10)(3) J
                                    = 6 J
Now, we can calculate the power of the boy as,
Power = `"Work done"/"Time"`
So , 
Power = `6/2` W
= 3 W
So, the power is 3 W.
Therefore, the answer is, (c) 3.0