An autographed baseball rolls off of a 1.4 m high desk & strikes the floor .53 m away from the desk. How fast was it. . .
rolling on the desk before it fell off? The accel. of gravity is 9.81 m/s^2.
Answer in units of m/s.
My original answer was 3.2 but was told that was wrong. What did I do wrong?
The key is to determine how long it took the ball to fall from the desk to the floor.
The relationship is:
delta y = Viy + 1/2 gt^2
When the ball rolls off the edge of the table, the initial velocity in the y-direction (Viy) is assumed to be zero.
So, it simplifies to: delta y = 1.2 gt^2
delta y = 1.4 m, g = 9.81 m/s/s and solve for t.
t = 0.53 s.
In 0.53 s, the ball went forward 0.53 m.
velocity = d/t = 0.53 m/0.53s = 1.0 m/s ball speed in the x-direction when it rolled off the table.