Abatter hits a pop-up straight up over home plate at an initial velocity of 21 m/s. the ball is caught by the catcher at the same height that it was hit. at what velocity does the ball land in the catcher's mitt? neglect air resistance. (take the positive direction to be upwards.)

Our intial velocity is -21 m/s

The computation for this problem would be:

vf² = vi² + 2ad 

vf = +/- sqrt[vi² + 2ad] 

since d = 0, 

vf = +/- sqrt[vi²] 

vf = +/- vi 

vf = -vi, from the time when the final velocity must be in the opposite direction of the initial velocity, the answer would be:

vf = - 21 m/s

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