Question

A man pushes a lawn mower on a level lawn with a force of 201 N. If 25% of this force is directed forward, how much power does he expend in pushing the mower 6.3 m in 14 s? answer in:_____W

Answer 1

We know that power is given by:

`\begin{gathered} P=(W)/(t) \\ \text{ where } \\ W\text{ is the work } \\ t\text{ is the time} \end{gathered}`

we also know that the work is given by:

`W=Fd`

where F is the force and d is the distance.

From the statement we know that only 25% of the force is directed forward, this means that the force that does work is:

`\begin{gathered} F=0.25(201) \\ F=50.25 \end{gathered}`

Now that we know the force we can find the work done by it if we multiply it by the 6.3 m the man pushes the lawn mower:

`\begin{gathered} W=(50.25)(6.3) \\ W=316.575 \end{gathered}`

Finally we plug this in the power formula and the time of 14 s given, then we have:

`\begin{gathered} P=(316.575)/(14) \\ P=22.61 \end{gathered}`

Therefore, the power expend by the man is 22.61 W (rounded to two decimal places)