Power P is the amount of energy E transferred or converted per unit time t, and is expression is:
P = E/t
The necessary energy to lift the box its the work of against the Gravity Force, and is given by:
E = mgh
Then the power is:
P = E/t
P = mgh/t
P = (45 kg)(9.8 m/s²)(1.7 m )/ 30
P = 24.99 W
P ≈ 25 W
