Question

A 125-lb student races up stairs with a vertical height of 4.0 m in 5.0 s to get to a class on the second floor. How much power in watts does the student expend in doing work agains gravity?

Answer 1

The formula to find the power is

`P=(W)/(t)`

Where W represents the work done, which is the product between the force exerted and the distance traveled, W=Fd. In this case, the force is the weight of the student.

`F=mg`

Let's replace the mass and the gravity, knowing that 125 pounds are equal to 56.7kg.

Once we have the force, we can find the work done

`\begin{gathered} W=556.23N\cdot4m \\ W=2,224.92J \end{gathered}`

Now we can use the work done to find the power in Watts

`\begin{gathered} P=(2,224.92J)/(5\sec ) \\ P=444.98W \end{gathered}`

Therefore, the power in Watts is 444.98.