baseball

yankee

An autographed baseball rolls off a 1.2m high desk & strikes the floor 0.37m away from the desk. The acceleration of gravity is 9.81m/s^2. How fast was it rolling on the desk before it fell off?

kreil

Analyze the problem vertically using the equation

[latex]d=v_it+\frac{1}{2}at^2[/latex]

since vi is zero, solving for time yields:

[latex]d=\frac{1}{2}at^2 \implies t=\sqrt{\frac{2d}{a}}[/latex]

Now, use this time to analyze the problem horizontally. It moved a total distance d in time t, so use the equation

[latex]v_i=\frac{d}{t}[/latex]

and this will yield the balls initial horizontal velocity.