A tennis ball is thrown vertically upward with an initial velocity of 8.0 m/s.
a) What will be its velocity when it returns to its starting point?
b) How long will it take to reach its starting point?
Answer (3)
-- The velocity of the ball when it plunks back into the thrower's hand will be the same 8.0 m/s but directed downwards this time.
-- Gravity robs 9.8 m/s from upward velocity each second. The ball can only stand this for (8.0 / 9.8) = 0.816 second (rounded) before it stops rising and begins to fall.
The round trip, from the thrower's hand, to the peak of the arc, and back to his hand, takes (0.816 x 2) = 1.633 second . (rounded)
The tennis ball will have a** velocity of -8.0 m/s** when it returns to its starting point, and it will take approximately 1.64 seconds for the ball to return to its initial point. ;
The velocity of the tennis ball when it returns to its starting point will be − 8.0 m/s (downward). It will take approximately 1.63 s to return to the thrower's hand. The motion can be analyzed using kinematics under the influence of gravity.
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