$A$ girl of mass $40\, kg$ climbs a rope $6\, m$ long at a constant speed in $15$ seconds. What power does she expend during the climb (in $W$)?

State whether the following statement is true or false:
When an arrow is released from a bow,potential energy changes into kinetic energy.

$A$ man of mass $60 \, kg$ runs up a flight of $30$ steps in $40 \, s$. If each step is $20 \, cm$ high,calculate the power of the man.

$A$ boy is moving on a straight road against a frictional force of $5\, N$. After travelling a distance of $1.5\, km$ he reaches a roundabout (Fig.) of radius $100\, m$. He moves on the circular path for one and a half cycles and then moves forward up to $2.0\, km$. Calculate the total work done by him against the frictional force.

The power of a motor pump is $2 \, kW$. How much water per minute can the pump raise to a height of $10 \, m$ (in $kg$)? (Given $g = 10 \, m \, s^{-2}$)

Define: $(a)$ power $(b)$ work done $(c)$ kinetic energy. Give the $SI$ unit of each.