Ok so this is a kinetic and potential energy problem. KE= 1/2*m*v^2 and PE= mgh so we set them equal to each other and get KE=PE so 1/2mv^2=mgh so mass divers out and left with 1/2v^2 =gh so solving for h or height we get
h=(1/2v^2)/g so h= 1/2*(6.5m/s)^2/9.80m/s^2 = 2.16m in height the ball will reach.
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