Answer to Question #4580 in Mechanics | Relativity for Marcus
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.
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.