1. When Burl stands alone in the exact middle of his scaffold, the left scale reads 500 N. Fill in the reading on the right scale. The total weight of Burl and the scaffold must be ___________N.
2. Burl stands farther from the left. Fill in the reading on the right scale.
3. In a silly mood, Burl dangles from the right end. Fill in the reading on the right scale.
Do your answers illustrate the equilibrium rule?
1.The total weight is 1000 N. The right rope must be under 500 N of tension because Burl is in the middle, and both ropes support his weight equally. Since the sum of upward tensions is 1000 N, the total weight of Burl and the scaffold must be 1000 N. Let’s call the upward tension forces 1000 N. Then the downward weights are -1000 N. What happens when you add 1000 N and 1000 N? The answer is they equal zero. So we see that \Sigma F=0 .
2. Did you get the correct answer of 830 N? Reasoning: We know from question 1 that the sum of the rope tensions equals 1000 N, and since the left rope has a tension of 170 N, the other rope must make up the difference—that 1000 N – 170 N = 830 N. Get it? If so, great. If not, discuss it with your friends until you do. Then read further.
3. The answer is 1000 N. Do you see that this illustrates \Sigma F=0 .