Question

You lift a bag of rice of 450N weight to height 1.2m and carry it a distance of 10m to the kitchen. How much work is done?

Answer 1

The work is done only in lifting the bag to the height 1.2m,

Work is given by

$W=F\times s$ $F$ is force $s$ displacement in direction of force.

$=450\times 1.2=540J$

and $noworkisdoneincarryingittothekitchen$, since in that case displacement is perpendicular to the force of gravity. Because displacement is horizontal to ground but force of gravity is downwards so both perpendicular to each other.