Question

8) Cheater knowing Fluid Dynamics? - Red Sox ace Jon Lester pitched against the St. Louis Cardinals in Game 1 of the 2013 World Series, scattering five hits while striking out eight players over 7.2 scoreless innings en route to an 8-1 Boston win for an early 1-0 series lead. But people noticed that he constantly rubbed the ball against the inside of his glove, maybe with resin or some other gel? Or trying to roughen the ball with a tiny piece of sand paper? If this were true, the following was what he had actually achieved in terms of fluid dynamics, EXCEPT: a. A ball with gel to make it smooth will create less surface shear stress and thus less drag. b. A roughened ball would make the flow's boundary layer undergo an earlier transition from laminar BL to turbulent BL, so that BL separation was delayed and thus a reduced drag - a faster pitch! c. The drag characteristics of the ball would change drastically with the gel, and so would the ball path - making it harder to hit. d. Vaseline on the ball could make the dirt particles stay while travelling - making it a "rough ball." 9) Froude number Fr = is important in open channel flow of water, because a. Open channel flow has a pressure that is different everywhere, b. Open channel flow is with a free surface and the flow is driven by gravity, c. gy represented a wave from bottom to surface. d. Wetted perimeter of water channel P can be a rough surface.

Answer 1

laminas BL, to turbulent Ans. 82 option A roughned ball would make the flow's boundary seperation was faster pitch . delayed and BL so that BL thus the reduced drag eando: the ball As chat happen when we soughen the turbulent boundar layer és csealed as round the ball. large tary ol amunt of repcranian smooth Rough laminas flow ugg turbulont Horo By creating this turbulant- lages seperation point decreases. As the result laminas flow is able to continue arround the ball thus producing low drag wake. - Lower the drag wake , lex drag force upon Purbulent flow is just behind the lover pressure directly behind the ball And helps in the ball. ball creating

taster pitch and in alr swing. Am c ophön ® open channel flow is with a free surface es driven by gravity and flow Reason: The open channel How is alcind of flow that takes place in rivers and conals where the driving fous are mainly +) Gravity force 2.) Einer hiat force, fil fr= froude's Number bot fr As Froude's number is the function of inesta fore and gravity force thus this is used in open channel flow. > And othes ophion in the ques hon ale charcuteswhic of open channel flow. Ans @ Ophon : Qudra pre

SO As shape and other condition ase some the surface roughners of channel most important cuiteria for comparison. becomes the where Velocity of How in a 국 no surfore roughness Channel minm 4 times the roughness of corrugated metal channel roughnes of breus metal Channel. Veor. 4J Voren metal channel the corrugated trus after with brass . replacing 4 core [D-AV ] . & brass becomes quadruple this flow ow rate

Answer to question number 10 depend on the surface roughnes provided in some cases. But flow will increase always.

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