As an object moves from point A to point B only two forces act on it: one force is nonconservative and does -30 J of work,the other force is conservative and does +50 J of work.Between A and B,
A)the kinetic energy of object increases,mechanical energy decreases.
B)the kinetic energy of object decreases,mechanical energy decreases.
C)the kinetic energy of object decreases,mechanical energy increases.
D)the kinetic energy of object increases,mechanical energy increases.
E)None of the above.

Question

Quizplus · Accepted Answer

The nonconservative force does negative work, which means it takes energy away from the object. The conservative force does positive work, which means it adds energy to the object. The total work done on the object is F1S1F1030 J + 50 J = -280 J. This means that the mechanical energy of the object decreases by 280 J. The kinetic energy of the object must also decrease, since the mechanical energy is the sum of the kinetic and potential energies.

As an Object Moves from Point a to Point B