Answers: (a) 177.5 N, (b) 195 N

With the box at rest, apply the 2nd Law to determine the initial tension in the top rope:


When the elevator accelerates upward, the ropes undergo a slight change in length. The top rope will stretch, but the bottom ropes will contract. The length of each bottom rope decreases by the same amount that the length of the top rope increases. Given that the ropes follow Hooke’s law, the change in tension is proportional to the change in length. Accordingly, given that the ropes are identical, the increase in the tension in the top rope will equal the decrease in the tension in each...

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