Presentation on theme: "Why does a cricket ball swing or a baseball curve?"— Presentation transcript:
1 Why does a cricket ball swing or a baseball curve? FLUID FLOWMOTION OF OBJECTS IN FLUIDSHow can a plane fly?Why does a cricket ball swing or a baseball curve?Why does a golf ball have dimples?web notes: lect6a.ppt flow4.pdf flight.pdf
2 Resultant FR Lift FL drag FD Motion of object through fluid FORCES ACTING ON OBJECT MOVING THROUGH FLUIDLift FLdrag FDResultant FRMotion of object through fluidFluid moving around stationary object
3 The pattern is symmetrical Uniform motion of an object through an ideal fluid ( = 0)The pattern is symmetrical FR = 0CABD
5 NO CURVE Drag force due to pressure difference low pressure region motion of airDrag force dueto pressure differencemotion of objectlow pressure regionrotational KE of eddies heating effect increase in internal energy temperature increasesNO CURVEDrag force is opposite to the direction of motionhigh pressure region
6 ball: curved flight flow speed (high) vair + v reduced pressure v motion of airDrag force dueto pressure differenceball: curved flightmotion of objectflow speed (high) vair + v reduced pressurevvair (vball)MAGNUS EFFECTflow speed (low) vair - v increased pressurevBoundary layer – air sticks to ball (viscosity) – air dragged around with ballhigh pressure regionlow pressure region
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