What is horsepower?

$A$ 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.

When an arrow is shot from its bow,it has kinetic energy. From where does it get the kinetic energy?

The work done on an object does not depend upon the

$(a)$ Define one watt.
$(b)$ $A$ lamp consumes $1000 \ J$ of electrical energy in $10 \ s$. What is its power?

Explain that a flying bird possesses both potential and kinetic energy and provide their expressions.