Question

As a 1.0-kg object moves from point a to point b, it is acted upon by a single conservative force which does -40 j of work during this motion. at point a the speed of the particle is 6.0 m/s and the potential energy associated with the force is +50 j. what is the potential energy (in j) at point b?

Answer 1

Answer: 90 J

Explanation:

Work is done on an object to make it move from point a to point b. This work done is the energy difference between point b and point a.

Work done = - Change in potential energy

Potential energy at point a, (P.E.)a = + 50 J

Potential energy at point b, (P.E.)b = ?

Work done, W = - 40 J

⇒ W = - [(P.E.)b - (P.E.)a]

⇒ - 40 J = - [(P.E.)b - 50 J]

⇒(P.E.)b = 40 J + 50 J = 90 J

Thus, potential energy at point b is 90 J.

Answer 2

Work done by conservative force = -(Change in potential energy), in any process

That implies,
                    -40 = -(x-50) ; where x is the final potential energy
                       x = 90 Joules