Question

Chapman's pitch was clocked at 105.1 [mph] (169.1 km/h), which is the fastest pitch ever recorded in MLB. A baseball diameter is 72.6 [mm] on average. Assume that the prevailing conditions were 22 degrees Celsius and 1 [atm]. Air viscosity is 18.2 [µPa*s]. Estimate the drag force in [N] and [lb_f  ] when the baseball is moving at that speed.

Answer 1

Data provided in the problem statement

Velocity of baseball ( u0 )= 105.1 mph = 169.1 km /h = 169 ( km/h) * ( 1000 m/ 1km ) * ( 1 h / 3600 s) = 46.94 m/s

Diameter of ball ( Dp ) = 72.6 mm = 0.0726 m

Air viscosity ( ) = 18.2 µPa*s = 0.0182 cP

Now drag force can be estimated by stokes law as