Transcript Forces
Circular Motion Circular Motion 1. Do Now 2. Videos – Julius Sumner Miller • https://www.youtube.com/watch?v=z3BSkMj1wL – Bill Nye • https://www.youtube.com/watch?v=YIipJW0Pcjo 3. Discussion 4. Checking in 5. Problem Solving Aspects of Circular Motion •Tangential speed: The speed of an object tangent to its circular path Aspects of Circular Motion •Uniform circular motion: when the tangential speed is constant Centripetal Acceleration •During uniform circular motion the velocity is changing as the direction changes In Action • Simulation – http://lrrpublic.cli.det.nsw.edu.au/lrrSecure/Sit es/LRRView/13996/13996_pop7.htm • Video – https://www.youtube.com/watch?v=Jpbgg2TR Cuw 10.2 Circular Motion and Speed Tangential speed depends on rotational speed and the distance from the axis of rotation. Which part of the turntable moves faster—the outer part where the ladybug sits or a part near the orange center? Centripetal Acceleration •The acceleration of an object directed towards the center of its circular motion 2 ac = _vt _ r Force and Circular Motion • The net force on an object in circular motion, directed towards the circles center • Can be called centripetal force. Fnet = mac 2 Fnet = _mvt _ r Force and Circular Motion • The net force (centripetal) is exerted by whatever is keeping the object in its circular path The force exerted on a whirling can is toward the center. No outward force acts on the can. • The “string” that holds the moon on its almost circular path is gravity. • Electrical forces provide the centripetal force acting between an orbiting electron and the atomic nucleus in an atom. • Anything that moves in a circular path is acted on by a centripetal force. Centripetal force holds a car in a curved path. a. For the car to go around a curve, there must be sufficient friction to provide the required centripetal force. b. If the force of friction is not great enough, skidding occurs. ‘Centrifugal Force’ •“Not Really” •It is an effect caused by the inertia of an object trying to stay in straight line motion 10.4 Centripetal and ‘Centrifugal’ Forces The only force that is exerted on the whirling can (neglecting gravity) is directed toward the center of circular motion. This is a centripetal force. No outward force acts on the can. 10.4 Centripetal and ‘Centrifugal’ Forces The can provides the centripetal force necessary to hold the ladybug in a circular path.