Question

13. (II) A 75-kg petty thief wants to escape from a third-story jail window. Unfortunately, a makeshift rope made of sheets tied together can support a mass of only 58 kg. How might the thief use this "rope" to escape? Give a quantitative answer.

Answer 1

Mass of thief m = 75kg Maximum tension in string = 58kg = 58 times 9.21 = 56898N mg- T 75 times 9.81- 58 times 9.81 = 75 times a a = 17 times 9.81/75 = 2.22 m/s^2 Thief will escape if he come down with an acceleration of 2.22 m/s^2 mv^2/r = mg times 7.45 v = squareroot 7.45gr = squareroot 7.45 times 9.81 times 11 v = 28.35 m/s therefore In revolution per second, w = 2 pi r /v = 2 times 3.14 times 11/28.35 therefore w = 2.436 rev./s