An Elevator Is Rising at Constant Speed

Multiple Choice

An elevator is rising at constant speed. Consider the following statements: I. the upward cable force is constant
II. the kinetic energy of the elevator is constant
III. the gravitational potential energy of the Earth-elevator system is constant
IV. the acceleration of the elevator is zero
V. the mechanical energy of the Earth-elevator system is constant

A) all five are true
B) only II and V are true
C) only IV and V are true
D) only I, II, and III are true
E) only I, II, and IV are true