A cricket ball is resting on a picnic table. There is a gentle wind moving at 1m s-1. Assuming that Stokes' law applies, how much force does the wind apply to the ball? The radius of a cricket ball is 3.6 cm and the viscosity of air is 1.8x10-5 Pa s.
A) 1.2x10-5 N
B) 2.4x10-4 N
C) 1.2x10-3 N
D) 2.4x10-2 N
E) 1.2x10-1 N
ANS

Question

Quizplus · Accepted Answer

Stokes' law for drag force is F = 6πηrv, where η is the viscosity, r is the radius, and v is the velocity. Substituting the given values: F = 6 * 1.8x10^-5 Pa s * 0.036 m * 1 m/s = 1.2x10^-5 N.

A Cricket Ball Is Resting on a Picnic Table