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Visitors at an amusement park watch divers step off a
Chapter 2, Problem 2.83(choose chapter or problem)
Visitors at an amusement park watch divers step off a platform 21.3 m above a pool of water. According to the announcer, the divers enter the water at a speed of 56 mi/h (25 m/s). Air resistance may be ignored.
(a) Is the announcer correct in this claim?
(b) Is it possible for a diver to leap directly upward off the board so that, missing the board on the way down, she enters the water at 25 m/s? If so, what initial upward speed is required? Is the required initial speed physically attainable?
Questions & Answers
QUESTION:
Visitors at an amusement park watch divers step off a platform 21.3 m above a pool of water. According to the announcer, the divers enter the water at a speed of 56 mi/h (25 m/s). Air resistance may be ignored.
(a) Is the announcer correct in this claim?
(b) Is it possible for a diver to leap directly upward off the board so that, missing the board on the way down, she enters the water at 25 m/s? If so, what initial upward speed is required? Is the required initial speed physically attainable?
ANSWER:(a) Suppose the final velocity of the diver is . Now we know that the initial velocity m/s, the acceleration due to gravity is and the distance travelled is .
Now from the dynamics we know that
Hence the velocity at which the diver will enter the water is 20.4 m/s.