How many watts are there in $1$ horsepower (in $watts$)?

What is the amount of work done by a force when a body moves in a circular path?

$(a)$ Give two conditions for work to be done.
$(b)$ What is the work done by frictional force on an object when dragged along a rough surface?
$(c)$ Relate power and work.
$(d)$ $A$ machine does $1960 \, J$ of work in $4 \, \text{minutes}$. What is the power?

Calculate the kinetic energy of a car of mass $750 \,kg$ moving with a velocity of $54 \,km \cdot h^{-1}$. Find the new kinetic energy of the car if a passenger of mass $50 \,kg$ sits in the car.

Name the practical unit of power in engineering.

State whether the following statement is true or false:
Work done by a force depends upon how fast work is done.