Question

Below you see four different situations and force diagrams for a circled system object for each situation. The first three involve an elevator. The fourth involves a box sliding over a smooth horizontal surface. In each case the initial velocity of the object is shown.

Consider: How can you make sure the motion of the elevator/box is consistent with the given force diagram? (Hint: what is the direction of the sum of the forces in each force diagram?) Explain your reasoning for each situation.

2 3 4 FconE Con El C on El S on B R on B Eon EV Eon B E on El E on El

Answer 1

In first diagram, the arrow of each force represent the strength of the Force sigma F - mt force = F_con El - F_EM E_1 = -ve (negative) means, the object decelerating in upward direction in speeding down the elevator sigma F = +ve, means the elevator accelerating in upward direction. sigma F = 0, means, the elevator not accelerating it is moving with constant velocity The box accelerating toward rightward.