Question

Potential energy of a body in position A is-40J. Work done by conservative force in moving the body from A to B is-20J. Find potential energy of the body in position B.

Answer 1

Answer

In the attachment ☺️

Answer 2

Potential energy of the body  in position B is -20 J

Explanation:

• Given the potential energy of the body in position A is -40 J
• Work done by the conservative force in moving the body from A to B is given as -20 J
• The concept being used here is work done by a conservative force is equal to the negative of the magnitude of change of potential energy

        So here the work done by the conservative force in moving the body from position A to position B will be equal to the negative of the difference of potential energy at A and at B  i.e.

             $work_{AB} = -(U_{B} -U_{A} )\\-20 J = - U_{B} - 40\\U_{B} =-40 + 20= -20$

                     So the potential energy at B is -20 J