일반물리학 1 — Force and Motion-I: Problem 41

41 Joyce needs to lower a bundle of scrap material that weighs 450 N from a point 6.2 m above the ground. For doing this exercise, Joyce uses a rope that will break if the tension in it exceeds 390 N. Clearly if she hangs the bundle on the rope, it will break and therefore Joyce allows the bundle to accelerate downward. (a) What magnitude of the bundle’s acceleration will put the rope on the verge of snapping? (b) At that acceleration, with what speed would the bundle hit the ground?