Question

A body is displaced from position A to position B. Kinetic and potential energies of the body at positions A and B are K_(A)=50J, U_(A)=-30J, K_(B)=-10J and U_(B)=20J. Find work done by (a) conservative forces (b) all forces (c)forces other than covservative forces.

Answer 1

The work done due to conservative, all forces and non-conservative forces are:

• A body is displaced from position A to position B.

• Kinetic and potential energies of the body at positions A and B are $K_A = 50 J\\ U_A = -30 J\\K_B = -10 J\\U_B=20J$

• Work done due to conservative force = - (Change in potential energy)

                                                                        = -(20 - (-30)) J

                                                                        = - 50 J

• Work done by all forces = Change in Kinetic Energy

                                                = (-10 - (50)) J

                                                = -60 J

• Work done by non-conservative forces = $(K_B + U_B) -(K_A +U_A)$

                                                                          = (-10+20)-(50-30)

                                                                         = -10 J