Because many fuels are fossil fuels they take millions of years to form and the known reserves are being used much faster than the new ones being made
1) Assuming an adult person has an average mass of m=80 kg, and assuming it takes about 30 seconds to climb 5 meters of stairs, the energy used by the person is

So the power output is

And since the estimate we made is very rough, we can say that the power output of the person is comparable to the power output of the light bulb of 100 W.
2) Based on the results we found in the previous part of the exercise, since the power output of the person is comparable to the power output of 1 light bulb of 100 W, we can say that the person could have kept burning only one 100-W light bulb during the climb.
Answer:
Explanation:
Given
Velocity of point is given by 
To get maximum or minimum velocity differentiate v w.r.t t

so
should be equal to zero


i.e. 