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Vertical Circular Motion. Roller Coaster. Roller Coaster. T. ma R. x. ma R. ma R. T. T cannot be negative, the bob will fall down!. T = 0; v cr. mg. mg. mg. mg. Twirling a Ball on a String Vertically. Non-uniform Circular Motion.
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T maR x maR maR T T cannot be negative, the bob will fall down! T = 0; vcr mg mg mg mg Twirling a Ball on a String Vertically
Non-uniform Circular Motion If an object is moving in a circular path but at varying speeds, it must have a tangential component to its acceleration as well as the radial one.
Sustained vertical spinning • Ever wonder what a bike tire feels like? • At constant speed, the centripetal acceleration is constant (v2/r), but the direction of gravity keeps changing! • Feel heavier at bottom than at top • This ride definitely turns your world around!
water NB,W Bucket of Water a WE,W
Bridges & Speed Bumps The curvature of the bridge/bump and your speed determines if you are going to stay on the bump (N>0) or if you are going to bump: fly off it!
m M Connected Bodies Two different masses (m < M) are connected by a string going through a tube. Predict what will happen when you whirl the lighter mass with constant but high speed. Base your prediction on the CM model. • Mass M will be falling down since it is heavier • Mass M will be moving up and then stop • Mass M will move up and then will fall down • It is impossible to whirl the lighter mass around
m y T x mg M Connected Bodies - Analysis q If the mv2/R is > Mg, the mass M will accelerate upwards. Notice, the mass m will always rotate so the string is not horizontal. It happens so T has a vertical component to cancel out the mg!