Answer: A ball is thrown straight up from the edge of the

Chapter 2, Problem 2.89

(choose chapter or problem)

A ball is thrown straight up from the edge of the roof of a building. A second ball is dropped from the roof 1.00 s later. Ignore air resistance. (a) If the height of the building is 20.0 m, what must the initial speed of the first ball be if both are to hit the ground at the same time? On the same graph, sketch the positions of both balls as a function of time, measured from when the first ball is thrown. Consider the same situation, but now let the initial speed v0 of the first ball be given and treat the height h of the building as an unknown. (b) What must the height of the building be for both balls to reach the ground at the same time if (i) v0 is 6.0 m>s and (ii) v0 is 9.5 m>s? (c) If v0 is greater than some value vmax, no value of h exists that allows both balls to hit the ground at the same time. Solve for vmax. The value vmax has a simple physical interpretation. What is it? (d) If v0 is less than some value vmin, no value of h exists that allows both balls to hit the ground at the same time. Solve for vmin. The value vmin also has a simple physical interpretation. What is it?