ericmazur / PnPbook

Tracking of typos, errors, and improvements for "The Principles and Practice of Physics"
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dimples on golf balls #71

Open JohnDenker opened 9 years ago

JohnDenker commented 9 years ago

In chapter 18 on page 474 it mentions the dimples on golf balls.

The reality diverges significantly from the description here. There is a lot of complexity, but everything I've ever read suggests that the main advantage has to do with boundary layer control, reducing separation and thereby improving pressure recovery, for reasons having nothing to do with backspin.

See e.g. http://www.aerospaceweb.org/question/aerodynamics/q0215.shtml

Suggestion: Lose the golf ball. It adds nothing over the baseball example anyway.

Suggestion You could instead mention that the physics of the breaking ball provides the second half of the explanation of how an airplane wing works. The means of setting up the circulation is different, but once there is circulation -- and forward airspeed -- there will be a force.