DynamicsofUniformCircularMotion匀速圆周运动的动力学.pptxVIP

DynamicsofUniformCircularMotion匀速圆周运动的动力学第1页/共18页 Centripetal AccelerationUniform circular motion emphasizes that velocity vector is constant – but the direction of this constant velocity is not constant.By definition, acceleration is the change in velocity over time. The “change in velocity” for an object in UCM is the change in the velocity vector. The acceleration that occurs is toward the center of the circle. It is the force that is pulling the object “in” 第2页/共18页 Centripetal AccelerationThe centripetal acceleration (the acceleration toward the center of a circle) of an object depends on the velocity of the object and the radius of the circle and is expressed as:ac = v2 rd = 100mHow fast would the outer most part of the space station have to spin in order to have a centripetal acceleration of 9.8 m/s2 第3页/共18页 How fast would the outer most part of the space station have to spin in order to have a centripetal acceleration of 9.8 m/s2 ?a = v2 / r a = 9.8 m/s r = 100m/2 = 50mSolving for v:v = \/~(a r) = \/~(9.8m/s2)(50m) = 22.1 m/sd = 100mA bobsled goes down a track, moving at a constant velocity throughout all three turns. At which turn will there be the greatest centripetal acceleration?AB CD – All the sameIf the bobsled moves at 35 m/s throughout the course and turn B has a radius of 20m and turn C is 50m how many G’s of acceleration is the sledder feeling through turns B C ?第4页/共18页 Centripetal ForceThe net force required to keep an object of mass m, moving at a constant velocity v, on a circular path. F = mv2 rNote that v2/r = accelerationA 50 kg person and a 100 kg person ride the “Enterprise” at Valleyfair. The ride has a radius of 7 meters and takes 4 seconds per revolution. How much centripetal force does each person feel at point A C?“Gondolas start out hanging from the ride, then go to a horizontal position by centrifugal force from the spinning ride, which then lifts to a verti