An elevator is hoisted by its cables at a constant speed is the total work zero, negative, or positive?
The total work is zero. Work is mass multiplied by its acceleration. Since it is moving at constant speed, there is no acceleration thus work is zero.
My gut feeling is positive. Zero would be if it didn't move at all, right And Negative would mean it is moving in the opposite direction, or something like that.
The elevator does work, contrary to many people! Actually, gravity pulls the elevator down. So, the cables exert a tension on the elevator to balance the force, mg, so that the elevator goes up with constant velocity. Since, the force (tension) and the displacement are in the same direction, the work done is positive.
