Question

$\left(i\right)$ Name the physical quantity measured in terms of horse power.
$\left(ii\right)$ A nut is opened by a wrench of length $20cm$. If the least force required is $2N$, find the moment of force needed to loosen the nut.
$\left(iii\right)$ Explain briefly why the work done by a fielder when he takes a catch in a cricket match is negative.

Answer 1

$\left(i\right)$ Horse Power (hp) is another unit of Power.
$1$ hp $=745.7$ watt
$\left(ii\right)$ Given: Force$=2N$, $d=20cm=0.2m$
Moment of force $=$ Force $\times$ distance
$=2\times 0.2$
$=0.4Nm$
$\left(iii\right)$ Work done is said to be negative when a force opposes the motion or tries to stop a moving body. Since the fielder tries to stop the moving ball, his work done is negative.