Factors Affecting Circular Motion Centripetal Force Factors Affecting Circular Motion

Recap

Curves, Centrifugal, Centripetal Forces Going around a curve smushes you against window Understand this as inertia: your body wants to keep going straight but the car is accelerating towards the center of the curve The Car accelerates  you think you’re being accelerated

Centripetal, Centrifugal Forces, continued The car is accelerated toward the center of the curve by a centripetal (center seeking) force The name for the “net force toward the center of the circle” that causes circular motion to occur NOT a separate force. Can use Fnet to represent it. In your reference frame of the car, you experience a “fake”, or fictitious centrifugal “force” Not a real force, just inertia relative to car’s acceleration Centripetal Force on car velocity of car (and the way you’d rather go)

Centripetal Force What provides it?

Car Around a Curve - Friction If there isn’t enough friction (icy or wet road), the car doesn’t make the curve!

Mythbusters!

Where v is the angular (rotational) speed

Fnet

The forces real and perceived Rotating Drum Ride Vertical drum rotates, you’re pressed against wall Friction force against wall matches gravity Seem to stick to wall, feel very heavy The forces real and perceived Real Forces: Friction; up Centripetal; inwards Gravity (weight); down Perceived Forces: Centrifugal; outwards Gravity (weight); down Perceived weight; down and out

Remember… Fnet

A 1500-kg car goes around a curve with a radius of 50 A 1500-kg car goes around a curve with a radius of 50.0-m at a speed of 8.0 m/s. a) How much Fc is needed?

A 50. 0-g cork on a 1. 00-m string twirls at 3. 00 rev/s A 50.0-g cork on a 1.00-m string twirls at 3.00 rev/s. The string can hold only 20.0-N. Will it break? IT WILL HOLD!!!