How much work is done by a weight lifter when he holds a weight of $80 \,kg$ on his shoulders for two minutes?

$A$ $1 \, kg$ mass has a kinetic energy of $1 \, J$ when its speed is: (in $, m/s$)

$(a)$ Define potential energy. Write an expression for potential energy of an object of mass $m$ raised through a height $h$.
$(b)$ Find the energy possessed by an object of mass $10 \, kg$ when it is raised to a height of $6 \, m$ above the ground. (Given $g = 9.8 \, m s^{-2}$)

Define kinetic energy and potential energy. Write an expression for $KE$ of a body of mass $m$ moving with speed $v$. Find the kinetic energy of a stone of $10 \, kg$ moving with a velocity of $10 \, m s^{-1}$.

$A$ boy of mass $40 \, kg$ runs up a flight of $50$ steps,each $10 \, cm$ high,in $5 \, s$. Find: $(i)$ the work done by the boy,and $(ii)$ the power developed. $(g = 9.8 \, m s^{-2})$

$(a)$ 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?