Mark out the correct statement(s).
A. Total work done by internal forces on a system is always zero
B. Total work done by internal forces on a system may sometimes be zero
C. Total work done by friction can never be zero
D. Total work done by friction is always zero
A. Total work done by internal forces on a system is always zero
B. Total work done by internal forces on a system may sometimes be zero
C. Total work done by friction can never be zero
D. Total work done by friction is always zero
Correct Answer – B
(b) Work done by friction mayt be positive, negative and zero. Work done by conservative, internal forces may be zero in a round trip but it is non-zero for non-conservative internal forces.