Circular Circular MotionMotion
Centri____ ForceCentri____ Force
Frequency vs. Period Period (T)- The time it
takes for one full rotation or revolution of an object in seconds.
Frequency (f)- The number or rotations or revolutions per unit time, measured in Hertz (Hz)
1 1T f
f T
How do we get
this equation?
2T
rv
T
Tangential Speed
CentriCentripetalpetal Force F Force Fcc
A force of some kind is required to A force of some kind is required to maintain circular motion. Why?maintain circular motion. Why?
Any force that causes an object to Any force that causes an object to follow a circular path is called a follow a circular path is called a centripetal forcecentripetal force..
Centripetal means “center-seeking”Centripetal means “center-seeking”Always acts inwardsAlways acts inwards
Centripetal Centripetal Acceleration aAcceleration acc
2T
c
va
r
Tangential Velocity
Radius
Centripetal ForceCentripetal Force
2
2
c c
c
Tc
F ma
F ma
va
r
mvF
r
ExamplesExamples
Friction is the centripetal force acting Friction is the centripetal force acting on a car driving around a curve.on a car driving around a curve.
Gravity is the centripetal force Gravity is the centripetal force causing the moon to orbit the Earth. causing the moon to orbit the Earth.
Centripetal force is not a new type of Centripetal force is not a new type of force. force. It is just the name given when a It is just the name given when a force causes circular motionforce causes circular motion by acting by acting at a right angle to an object’s motion.at a right angle to an object’s motion.
A ball is attached to a string and is A ball is attached to a string and is spinning in a circle. The string spinning in a circle. The string breaks. Why does it fly off at a breaks. Why does it fly off at a
tangent?tangent? Because NO FORCE acts upon it!Because NO FORCE acts upon it!
Centrifugal force is a Centrifugal force is a fictitious forcefictitious force. It is an . It is an effect of rotation. effect of rotation.
How might centrifugal force replace How might centrifugal force replace gravity?gravity?