Question

A person bridge a mass of $2$ kg from A to B. The increase in kinetic energy of the mass is $4$ j and the work done by the persons on the mass is $-10$ J. The potential energy difference between B and A is

Answer 1

If the A and B are horizontal to the ground, the potential difference between point A and B will be zero, as because there is no change in height. Potential energy between two points is directly proportional to height.

And, if the mass is brought vertically from A to B, then

We know that, Work done=$mgh$------- (1)

Given $W=-10J$

(1)=> -10= $m\times g\times h$ = $2\times 10\times h$

(Considering g= $10m/s^2$)

=>h=$\frac{W}{mg}=\frac{10}{20}=\frac{1}{2}$unit

Therefore Potential energy difference between A and B is also 10J