Chapter 10.1, Problem 11PP

a.

To determine

Power developed.

Answer to Problem 11PP

Power developed is $348\text{W}$

Explanation of Solution

Given:

Applied force horizontally is $F=145\text{N}$

Distance covered at constant speed is $d=60\text{m}$

Force applied time is $t=25\text{s}$

Formula used:

Power developed is given by,

  $P=\frac{W}{t}$ ….. (1)

Calculation:

As, $W=Fd$

Putting $W$ in (1)

So,

  $\begin{array}{l}P=\frac{Fd}{t}\\ =\frac{145\times 60}{25}\\ =348\text{W}\end{array}$

b.

To determine

Power developed.

Answer to Problem 11PP

Power developed is doubled i.e. $P=696\text{W}$

Explanation of Solution

Given:

Applied force horizontally is $F=145\text{N}$

Distance covered at constant speed is $d=60\text{m}$

Time is halved i.e. Force applied time is $t=12.5\text{s}$

Formula used:

Power developed is given by,

  $P=\frac{W}{t}$ ….. (1)

Calculation:

As, $W=Fd$

Putting $W$ in (1)

So,

  $\begin{array}{l}P=\frac{Fd}{t}\\ =\frac{145\times 60}{12.5}\\ =696\text{W}\end{array}$

i.e. whent is halved, power is doubled.