circular motion

uniform circular motion

• an object moves at a constant speed at a constant distance from the center (a circle)

• the object constantly changes direction due to an UNBALANCED force directed toward the center - called CENTRIPETAL FORCE

  • not rotational motion

• 2 forces: tension inward and gravity outward

• accelerating b/c changing velo. b/c changing direction

moon traveling in circular path around a planet

• planet exerts a gravitational force on the moon that is inward toward the center, which provides the centripetal force

• at every point in its motion, the object is moving in a straight line due to inertia, but the centripetal force turns it - changing its direction but not speed

in every case of an object moving in a circle there must be

a constant unbalanced force exerted on the object that is directed outward toward a central point at a constant distance (radius)

what provides the centripetal force in a ball being spun in a horizontal circle on a string

tension in the string

what provides the centripetal force of a person riding the Finnish fling at worlds of fun

normal force from sides of the “tub”

what provides the centripetal force of a satellite in orbit around earth

gravitational force OF the Earth on the satellite

what provides the centripetal force of clothes being spun in a washing machine

normal force from the sides of the tub

what provides the centripetal force of a car riunding a corner on a level road

• vertical forces: equilibrium

• horizontal force: friction force of the road on the tires

what provides the centripetal force of a race car rounding a banked curve (tilted inward) when surface is covered with fuel and tire particles

• a component of the normal force of the ground on the tires that points to the center if the circular path

geosynchronous

• used to define the satellites position in relation to the earth. they orbit at just the right distance and just the right speed so they orbit at the same rate that the earth rotates

  • they are always above the same spot on the earth… good for communications

weightlessness

• what an astronaut in a space shuttle experience

• only experience this because them, the shuttle, and everything/everyone on board are all in free fall (accelerating towards the earth)

• they don’t hit the earth because the tangential velocity of the shuttle is large enough that they fall towards the earth and miss

• the shuttles orbit

tangential velocity

• the linear speed of an object moving along a circular path

• point at edge of turntable covers greater distance than point at middle

• spinning a string in a circle letting go - object will move in a straight line

  • space shuttle

space shuttle tangental velocity

• shuttle is in stable orbit because it is falling towards the earth but is missing it - the movement away is equal to the movement down due to gravity