Homework Help: physics

Posted by rista on Friday, May 20, 2011 at 11:10pm.

a ball is projected horizontally from the edge of a table that is 0.433m high, and it strikes the floor at a point 1.84m from the base of the table. the acceleration of gravity is 9.8m/s^2.what is the initial speed of the ball? how high is the ball above the floor when its velocity vector makes a -18.9486 angle with the horizontal?
i got initial speed that is 6.13 m/s. but i dont know to find another question.. please help...

physics - drwls, Friday, May 20, 2011 at 11:24pm
The time it takes to hit the ground is
t = sqrt(2H/g) = 0.2973 s
The speed when it leaves is the constant horizontal component
Vx = 1.84/0.306 = 6.19 m/s

When the velocity vector angle is -18.9486 degrees below horizontal, the ratio Vy/Vx is the tangent of 18.9486 degrees, which is 0.3433

Therefore Vy = 2.13 m/s at that time.
The time after leaving is
t' = 2.13/g = 0.217 s

Use that time to calculate the distance it has fallen, and from that, the height above the floor.
physics - rista, Saturday, May 21, 2011 at 12:25pm
hey i tried bt i didnt got the answer.. can u help more to get answer.. please

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