Which of the following statements is TRUE for a system comprising of two bodies in contact exerting frictional force on each other :
Select all that apply

Question

Which of the following statements is TRUE for a system comprising of two bodies in contact exerting frictional force on each other :

G1 Physics · Accepted Answer

For static friction, the two contact points have no relative slip, so the internal action-reaction friction pair does zero net work on the complete system. For kinetic friction, relative slip causes irreversible loss of mechanical energy, so the total internal friction work is negative. Hence A,D.