Question #4580

Randy Johnson throws a baseball horizontally from the top of a building as fast as his 2004 record of 102.0 mph (45.6 m/s). How much time passes until it moves at an angle 13.0 degrees below the horizontal? Ignore air resistance.

Expert's answer

Let Vx = 45.6 m/s be the horizontal component of the velocity and Vy - vertical

component. Vx doesn't change with time because we ignore air resistance.

Vy

changes with acceleration g=9.8 m/s^2. So, Vy(t) = gt. We need Vy / Vx =

tan(13.0). So, gt = Vx*tan(13.0).

t = Vx*tan(13.0)/g = 45.6*tan(13.0)/9.8 =

1.07 seconds.

component. Vx doesn't change with time because we ignore air resistance.

Vy

changes with acceleration g=9.8 m/s^2. So, Vy(t) = gt. We need Vy / Vx =

tan(13.0). So, gt = Vx*tan(13.0).

t = Vx*tan(13.0)/g = 45.6*tan(13.0)/9.8 =

1.07 seconds.

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