Uniform Circular Motion
Centripetal force, tangential velocity, and motion in a circular plane
Uniform Circular Motion - an object moving at constant speed along a circular path, continuously turned by a center-directed force
“What does this picture tell you about the speed of these motorcyclists?”
www.webbikeworld.com
“A large centripetal (center directed) force in needed to turn at high speeds.”
The rider needs to lean when they go around a turn at high speeds to counteract the large centripetal force provided by the centripetal force of the tires.
I. Uniform Circular Motion
Why can it be said that the earth has a nearly uniform circular motion around the sun?
The earth moves in a plane around the sun. Define the geometric shape called a plane.
The earth and a motorcycle need something in order to turn. What is that?
The Physics of Countersteering
Force on an Object Moving in a Circle
Show Me The Physics YouTube Channel
Show Me The Physics
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In order for an object to move at constant speed in a circle, an outside force must constantly turn the object toward the center of circular path.
Circular Motion, Car on a Banked Track
by Dr. Michael R. Gallis mrg3@psu.edu
Penn State Schuylkill
Go Nittany Lions!! 
Draw the Centripetal Force and Tangential Velocity
Draw the centripetal force, and tangential velocity
Draw the centripetal force, and tangential velocity
B
NYSSLS Reading Passage · Circular Motion
Falling Sideways: The Hidden Physics of Turns, Loops, and Orbits
Open Reading Passage → Regents Practice Version →Check Your Understanding
5 quick questions — pick an answer to see if you’re right.
1. Which best describes uniform circular motion?
2. In what direction does the centripetal force on an object moving in a circle point?
3. At any instant, what is the direction of the velocity of an object moving in a circle?
4. A ball is swung in a horizontal circle on a string and released. Which path does it follow right after release?
5. Why must the Earth have a force acting on it to orbit the Sun at nearly constant speed?
Riding a Carousel
A child rides a carousel horse located 6.0 m from the center. The carousel turns at a steady rate, completing one revolution every 12 s.
Which statement about the child’s motion is correct?
▶ Want a challenge? Open 6 more Regents-style questions (harder · mixed formats)
Challenge score: 0 / 6
C1. The child says she “feels pushed outward.” Which explanation is correct?
C2. Substitute numerical values into a mathematical representation that can be used to determine the child’s speed. Then calculate the speed.
C3. Viewed from above, the center of the carousel is directly below the child on your screen (the child is at the top of the circle). The child has a mass of 30. kg. Choose the direction of the net force on the child, and determine its magnitude.
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C4. A student makes the following claim.
Place a check mark in either the Support or Refute box. Justify your response using a mathematical relationship.
C5. A second child sits on a horse 3.0 m from the center. How do the two children compare?
C6. Carousel operators often seat the youngest children on the inner horses. Using the relationships for circular motion, explain why the inner horses give a gentler ride.
