Circular Motion,Uniform circular motion: examples include Objects in orbit (earth around the sunDriving a car around a cornerRotating a ball around on a string,Circular Motion,According to Newtons mechanics, objects dont tend to move in a circle by themselves. They tend to either be at rest of move in a straight line at constant speed (this is Newtons first law),Circular Motion,Circular motion is not “natural” motionSome (a Force) must make an object move in a circleThe Force causing circular motion can be one of many different forces, depends on the situation (orbit = gravitational force, car turning a corner = frictional force, ball on a string = tension force),Circular Motion,Remember from Newtons 2nd law, that .Force = mass x acceleration (F = ma)But if the object is in uniform circular motion, their speed is constant, so is acceleration = 0?,Circular Motion,In circular motion, the acceleration is a change in the direction of the object, even though the speed is constant, the direction keeps changing, and velocity is a vector. The force keeps pulling the object to the center, hence we call this type of acceleration “centripetal” acceleration which means “center seeking”.,Circular Motion,Solving circular motion problems is like a typical “force” problem where the motion is circular rather than linear.F = ma still works, now we have a new term for centripetal accelerationac = v2/r acceleration (centripetal) = velocity squared/radius.,