$A$ block of mass $5 \,kg$ is lying on a frictionless table. $A$ force of $20 \,N$ is applied on it for $10 \,s$. Calculate its kinetic energy. (in $J$)

$A$ 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 potential energy of a person is minimum when:

$A$ body is falling from a height $h$. After it has fallen a height $\frac{h}{2}$,it will possess

What is a watt?

$(a)$ What is the commercial unit of energy? Give its relationship with the $SI$ unit of energy.
$(b)$ An electric bulb of $60 \,W$ is used for $10$ hours every day. How many units of electrical energy are consumed by this bulb in one day?