Posted: September 12th, 2015

Bob has just finished climbing a sheer cliff above a beach, and wants to figure out how high he climbed.

Bob has just finished climbing a sheer cliff above a beach, and wants to figure out how high he climbed. All he has to use, however, is a baseball, a stopwatch, and a friend on the ground below with a long measuring tape. Bob is a pitcher, and knows that the fastest he can throw the ball is 91.0 mph. Bob starts the stopwatch as he throws the ball (with no way to measure the ball\’s initial trajectory), and watches carefully. The ball rises and then falls, and after 0.710 seconds the ball is once again level with Bob. Bob can\’t see well enough to time when the ball hits the ground. Bob\’s friend then measures that the ball landed 387 ft from the base of the cliff. How high up is Bob, if the ball started from exactly 5 ft above the edge of the cliff?