In: Physics
A boy tosses a football upward. If the football rises a vertical distance of 6.9m and the boy catches it at the same point he released it, what is the velocity of the ball just before he catches it? (Assume upward is the positive direction. )
While the ball is in air, acceleration of the ball is
acceleration due to gravity 
Since the ball is caught at the point of projection displacement
is zero. 
Using the equation 
as 

Hence 
Since direction of initial and final velocity are opposite to each other.

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Now applying the same equation, at top and bottom of trajectory
velocity at the top is 
Displacement 




Initial velocity is 
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Final velocity is 
Negative sign indicates that velocity is downwards