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Explore the dynamics of circular motion, including acceleration, forces, and orbits. Solve problems and learn about Newton's laws and gravity. Special assignment included. Sample question on vertical loop motion.
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Lecture 16Friday, October 3 Chapter 6: Circular Motion
Review Example Macie pulls a 40 kg rolling trunk by a strap angled at 30° from the horizontal. She pulls with a force of 40 N, and there is a 30 N rolling friction force acting on trunk. What is the trunk’s acceleration? Slide 5-17
For uniform circular motion, the acceleration • Is parallel to the velocity • Is directed towards the center of the circle • is larger for a larger orbit at the same speed
Problem, interacting bodies Glider on a air track Massless, frictionless pulley m1 m2
Special Assignment • Special assignment to be handed in Monday: Workbook pages 4-5 and 4-6, exercises 17-22 and page 5-5, exercises 13-15.
Chapter 6 Circular Motion, Orbits and Gravity Topics: • The kinematics of uniform circular motion • The dynamics of uniform circular motion • Circular orbits of satellites • Newton’s law of gravity Sample question: The motorcyclist in the “Globe of Death” rides in a vertical loop upside down over the top of a spherical cage. There is a minimum speed at which he can ride this loop. How slow can he go? Slide 6-1
Uniform Circular Motion • Uniform magnitude of velocity (speed) is constant
Circular Motion • Note similarity to the equations for one-dimensional linear motion
UCM continued • Travelling at constant speed v around circle • Period is time one around circle = T
UCM cont • s is distance travelled around circumference and the definition of the radian tell us
Uniform Circular Motion • Uniform magnitude of velocity (speed) ω, is constant • But α is not zero because direction of velocity is changing.
Uniform Circular Motion Slide 6-13
Newton’s Second Law • Net force must point towards center of circle
Example A level curve on a country road has a radius of 150 m. What is the maximum speed at which this curve can be safely negotiated on a rainy day when the coefficient of friction between the tires on a car and the road is 0.40? Slide 6-24
Top View • v
Checking Understanding When a ball on the end of a string is swung in a vertical circle: • What is the direction of the acceleration of the ball? • Tangent to the circle, in the direction of the ball’s motion • Toward the center of the circle Slide 6-11
Problems due today • 5: 24, 25, 29, 30, 31, 35, 36, 37, 39