Question

A crane with output power of 200W will lift a 600N object a vertical distance of 4.0 meters in seconds

Answer 1

Power is calculated by dividing energy with time (J/s) or Watts
In this case, The energy is given by mgh where mg is the weight and h is the vertical height.
Thus, Energy = 600 × 4 = 2400 Joules
Power = Energy /time
Time will therefore be Energy/power
= 2400 J/ 200
= 12 seconds