A ball is rolled off the edge of a swimming pool and strikes the water 2.0 m away 0.30 seconds later. What was the initial speed of the ball? its speed when it strikes the water?

Question

souvik · Answer

at position A the vertical velocity of the ball is zero..
when the ball strikes the water the horizontal velocity does not change as there is no horizontal acceleration..
so $\huge{v _{x}}$=2/0.30=20/3 m/s
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let the vertical displacement of the ball be $h$ 
so $h$=1/2$gt^2$
when the ball strikes the horizontal velocity of the ball be $v _{y}$
so $v _{y}=gt$
so the velocity of the ball when it strikes water $v=\sqrt{v _{x}+v _{y}}$