Chapter 8 Rotational Motion.

Slides:



Advertisements
Similar presentations
In the absence of an external force, the momentum of an object remains unchanged—conservation of momentum. In this chapter we extend the law of momentum.
Advertisements

Centripetal force keeps an object in circular motion.
Ch08-Rotation - Revised 3/7/2010
10 Circular Motion Centripetal force keeps an object in circular motion.
1 Circular Motion. the motion or spin on an internal axis.
Rotational Motion.
Chapter 8 Rotational Motion 1.CIRCULAR MOTION Which parts on a merry-go-round move fastest? Which have greater rotational speeds? Examples of rotational.
Warm Up Ch. 9 & 10 1.What is the relationship between period and frequency? (define and include formulas) 2.If an object rotates at 0.5 Hz. What is the.
Rotational Inertia and Angular Momentum. Inertia The resistance of an object to change its state of motion Depends on mass (the bigger the mass, the bigger.
 What is a ‘lever arm’?  Distance from the axis of rotation to where a force is applied.
Rotational Motion.
Chapter 11 Rotational Mechanics. Torque If you want to make an object move, apply a force. If you want to make an object rotate, apply a torque. Torque.
Chapter 9 Circular Motion.
Chapter 8 – Rotational Motion
Chapter 11 Rotational Mechanics Rotational Inertia n An object rotating about an axis tends to remain rotating unless interfered with by some external.
Chapter 8 Rotational Motion, Part 2
Physics Announcements WebAssign – –Chapter 7 due today Exam #2 not graded yet Picture: 30-m Darrieus Wind turbine in the Magdalen Islands.
Chapter 8 Rotational Motion Forces and circular motion Circular motion = accelerated motion (direction changing) Centripetal acceleration present Centripetal.
Welcome to Jeopardy! Please raise your hand to answer. An answer must be in the form of a question. Each correct answer is worth five extra credit points.
Rotation of rigid objects- object with definite shape
Gravitation Attractive force between two masses (m 1,m 2 ) r = distance between their centers.
Cheyanne Rimer, Jeremy Massari, William Ortiz, Jordan Cooper, and Duncan Godsey Rotational Mechanics.
© 2010 Pearson Education, Inc. Chapter 8: ROTATION.
Circular and Centripetal Motion
Chp 9-11 Rotational Motion. Some Vocab Terms  Axis – the straight line around which rotation takes place  Rotation – when an object spins around an.
1 Physics 1100 – Spring 2009 Review for Exam I Friday, February 27 th Chapters
Chapter 8 Rotational Motion 1.CIRCULAR MOTION Which parts on a merry-go-round move fastest? Which have greater rotational speeds? Examples of rotational.
© 2010 Pearson Education, Inc. Conceptual Physics 11 th Edition Chapter 8: ROTATION Circular Motion Rotational Inertia Torque Center of Mass and Center.
Circular Motion Unit 5. An axis is the straight line around which rotation takes place. When an object turns about an internal axis- that is, an axis.
Rotation & Centripetal Force
 Rotation – object spinning around an internal axis. Ex: a spinning top  Revolution – object spinning around an external axis. Ex: Earth moving around.
Rotational Motion. Tangential and Rotational Velocity.
Chapter 8 - R o tati o nal M o ti o n Circular M o ti o n.
10 Circular Motion Centripetal force keeps an object in circular motion.
Conceptual Physics Notes on Chapter 9 CircularMotion.
Rotational Motion Chapters 10, 11, & 12. Rotation vs Revolution An axis is the straight line around which rotation takes place. When an object turns about.
Chapter 8 Rotational Motion. Angular Distance (  ) o oReplaces distance for rotational motion o oMeasured in Degrees Radians Revolutions 
Rotational Dynamics Chapter 8 Section 3.
© 2010 Pearson Education, Inc. Conceptual Physics 11 th Edition Chapter 8: ROTATION.
Chapter 11 Rotational Mechanics. Recall: If you want an object to move, you apply a FORCE.
Circular Motion. Rotation and Revolution When a body turns about it’s axis is known as a rotation. When a body turns about it’s axis is known as a rotation.
Angular Mechanics Chapter 8/9 Similarities LinearAngular MassMoment of Inertia ForceTorque MomentumAngular Momentum.
Angular Mechanics Chapter 8/9 Similarities LinearAngular MassMoment of Inertia ForceTorque MomentumAngular Momentum.
 Rotation – when an object turns about an internal axis.  Think of this as spinning  Revolution – when an object turns about an external axis.  Think.
Chapter 9 Circular Motion. Axis – Central point around which rotation occurs (axis) (fulcrum) Rotation – occurs when an object turns about an internal.
Circular Motion Physics Mr. Padilla. Rotation and Revolution Both rotation and revolution occur by an object turning about an axis. Rotation - The axis.
Rotational Mechanics Rotational Motion Rotational Speed or Angular Speed Typically measured in rpm’s or degrees/sec, but the SI unit is radians/sec ω.
Circular Motion, Center of Gravity, & Rotational Mechanics
Chapter 9 Circular Motion. Axis: The straight line about which rotation takes place Rotation: Spin, when an object turns about an internal axis Revolution:
Conceptual Physics Chapter 10
Physics Chapter 8 – Rotational Motion Part 2. Review of Circular Motion Tangential Speed vs Rotational Speed Tangential Speed vs Rotational Speed Rotational.
Circular Motion. Rotation vs. Revolution Rotation – when an object turns about an internal axis. – Think of this as spinning Revolution – when an object.
Rotational Mechanics. Torque When you want an object to turn or rotate, you apply a torque. Torques produce rotation.
Bell Ringer In terms of energy, what happens to the energy of an object in free-fall?
Angular Momentum Chapter Notes. Angular Momentum Recall that linear momentum is equal to an object’s mass times its velocity Anything that rotates.
© 2010 Pearson Education, Inc. Conceptual Physics 11 th Edition Chapter 8: ROTATION.
Elizabeth, Colby, Ashley, Brittany. State and Explain Concepts  Torque is the tendency of a force to cause rotation about an axis.  Lever arm is he.
Circular Motion. Rotating Turning about an internal axis Revolving Turning about an external axis.
Rotation and Revolution In this unit we will be investigating objects moving in a circular path about an axis. We will see two types of motion: – Rotation.
Circular Motion Or I go right round baby right round like a record baby right, right, right, round?
Circular Motion. Two types of Spin Rotation occurs when object spins around internal axis that is attached to object. – E.g. Merry-go-round, rotating.
Chapter 9 Circular Motion.
Lec 08: Rotation Rotation: Angles, Speed
Chapter 10 Circular Motion.
Circular Motion
Rotational Motion Rotational Inertia – inertia is how an object resists changing its motion so rotational inertia is how much an object resists changing.
Uniform Circular Motion
Circular Motion Chapter 10.
Circular Motion Unit III Chapter 9.
Uniform Circular Motion
Presentation transcript:

Chapter 8 Rotational Motion

Rotational Inertia An object rotating about an axis tends to remain rotating unless interfered with by some external influence. This influence is called torque. Rotation adds stability to linear motion. Examples: spinning football bicycle tires Frisbee

The greater the distance between the bulk of an object's mass and its axis of rotation, the greater the rotational inertia. Examples: Tightrope walker Inertia Bars Ring and Disk on an Incline Metronome

Torque Torque is the product of the force and lever-arm distance, which tends to produce rotation. Torque = force ´ lever arm Examples: wrenches see-saws

Center of Mass The center of mass of an object is the average position of mass. Objects tend to rotate about their center of mass. Examples: Meter stick Map of Texas Rotating Hammer

Stability For stability center of gravity must be over area of support. Examples: Tower of Pisa Touching toes with back to wall Meter stick over the edge Rolling Double-Cone

What is that force that throws you to the right if you turn to the left in your car? It’s a “center-fleeing” force called centrifugal force. What is that force that keeps you in your seat when you turn left in your car? It’s a “center-seeking” force called centripetal force.

Direction of Motion Centripetal Force Centrifugal Force

Centripetal Force Centrifugal Force …is applied by some object. Centripetal means "center seeking". Centrifugal Force …results from a natural tendency. Centrifugal means "center fleeing".

Examples Centripetal Force Centrifugal Force water in bucket moon and earth car on circular path coin on a hanger jogging in a space station Bucket Earth’s gravity Road Friction Hanger Space Station Floor Nature

Conservation of Angular Momentum angular momentum = rotational inertia ´ rotational velocity L = I w Newton's first law for rotating systems: “A body will maintain its state of angular momentum unless acted upon by an unbalanced external torque.”

Examples: 1. ice skater spin 2. cat dropped on back 3. Diving 4. Collapsing Stars (neutron stars)

End of Chapter 7

To compute your grade… (This information is on the syllabus.) Homework Average _____ ´ 40 = _______ Exam 1 _____ ´ 150 = _______ Exam 2 _____ ´ 150 = _______ Lab Exam 1 _____ ´ 50 = _______ Exam 3 _____ ´ 150 = _______ Final Exam _____ ´ 150 = _______ Lab Exam 2 _____ ´ 50 = _______ Lab Grades _____ ´ 100 = _______ Total = _________  8 Your Average = _________

Notice The Physics 101 lab grades are posted outside of your lab room. You can pick up your old labs there as well. Use your old labs and the notes on the study guide to prepare for the lab exam. You can pick up you homework and in-class assignments outside of Dr. Bruton’s office (room 330).

Circular Motion Linear speed - the distance moved per unit time. Also called simply speed. Rotational speed - the number of rotations or revolutions per unit time. Rotational speed is often measured in revolutions per minute (RPM).

The linear speed is directly proportional to both rotational speed and radial distance. v = w r What are two ways that you can increase your linear speed on a rotating platform? Answers: Move away from the rotation axis. Have the platform spin faster.

Example Question Two ladybugs are sitting on a phonograph record that rotates at 33 1/3 RPM. (a) Which ladybug has a great linear speed? Answer: The one on the outside edge. (b) Which ladybug has a great rotational speed? Answer: Both have the same rotational speed.

Example Question Answer: 4 m/s Answer: 20 RPM You sit on a rotating platform halfway between the rotating axis and the outer edge. You have a rotational speed of 20 RPM and a tangential speed of 2 m/s. What will be the linear speed of your friend who sit at the outer edge? Answer: 4 m/s What will be his rotational speed? Answer: 20 RPM