Problem 3:

You have been hired as a technical consultant on a movie about Galileo. In one scene the main actor stands at the top of a tower and throws a rock at an angle of elevation of 30 degrees, towards a group of actors below. The script calls for the rock to land 20 m from the base of the tower. It should also take 3 s for the rock to reach the ground after the actor throws it (to allow time for a good expressive close-up). There is some concern that the rock will strike the ground with too much speed, causing cement chips to fly from the cement plaza and injure some of the actors. Determine the speed of the rock at impact.