Angular Momentum & Conservation

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Video Clips

Video RealVideo®
8:18 minutes (0:00 - 8:18)

Definition; calculating L from different frames; conservation of L from circle center.

Instructor: Prof. Walter Lewin
Prior Knowledge: Uniform Circular Motion (beginning of V5)
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Video RealVideo®
9:18 minutes (8:18 - 17:36)

Proof that dL/dt = r × f; angular momentum conserved when τ = 0; spin angular momentum defined.

Instructor: Prof. Walter Lewin
Prior Knowledge: Angular Momentum (beginning of V20)
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Video RealVideo®
7:58 minutes (17:36 - 25:34)

Angular momentum conservation calculation and demo for spinning person, with arms outstretched and pulled in.

Instructor: Prof. Walter Lewin
Prior Knowledge: Conservation of Angular Momentum (8:18 of V20)
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Video RealVideo®
9:58 minutes (25:34 - 35:32)

Definition; white dwarf, neutron star, black hole properties; energy released in a supernova.

Instructor: Prof. Walter Lewin
Prior Knowledge: Conservation of Angular Momentum (8:18 of V20)
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Video RealVideo®
7:36 minutes (0:00 - 7:36)

Conservation of angular momentum in general systems and in Earth's orbit; τ = 0 at center of revolution.

Instructor: Prof. Walter Lewin
Prior Knowledge: Conservation of Angular Momentum (8:18 of V20)
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Video RealVideo®
6:34 minutes (7:36 - 14:10)

Angular momentum of a rod revolving around the center of mass and a point off the CM; conservation of L only for CM.

Instructor: Prof. Walter Lewin
Prior Knowledge: Conservation of Angular Momentum (8:18 of V20)
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Video RealVideo®
11:30 minutes (14:10 - 25:40)

Speed of center of mass and angular velocity of rod after impulse at non-CM point, using two different origins; demonstration of motion.

Instructor: Prof. Walter Lewin
Prior Knowledge: Angular Momentum of Spinning Rod (7:36 of V21)
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Video RealVideo®
3:23 minutes (44:19 - 47:42)

Demonstration of blue plastic spinner that stops and spins in the opposite direction, apparently violating laws of physics.

Instructor: Prof. Walter Lewin
Prior Knowledge: Conservation of Angular Momentum (8:18 of V20)
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Lecture Notes

Document PDF - 1.6 MB#
Page 1 to page 2

Rotation about a fixed axis; definitions of angular velocity and angular acceleration; right-hand rule; rotational motion with constant angular accleration; relationship between angular velocity, linear velocity, and acceleration, with example.

Instructor: Prof. Stanley Kowalski
Prior Knowledge: Lecture 17
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Document PDF - 1.6 MB#
Page 3 to page 6

Definition of rotational kinetic energy, with example; definition of moment of inertia for a rigid body; moment of inertia example.

Instructor: Prof. Stanley Kowalski
Prior Knowledge: Rigid Body Kinematics
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Document PDF - 1.6 MB#
Page 1 to page 4

Parallel-axis theorem, with example; perpendicular-axis theorem, with examples; definition of angular momentum of a particle; definition of central forces; angular momentum of a particle moving in a straight line; angular momentum of a particle in uniform circular motion; angular momentum of a conical pendulum.

Instructor: Prof. Stanley Kowalski
Prior Knowledge: Lecture 21
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Document PDF - 1.6 MB#
Page 4 to page 6

Relationship between forces and angular momentum; definition of the law of conservation of angular momentum; definition of torque; angular momentum and central forces, with examples.

Instructor: Prof. Stanley Kowalski
Prior Knowledge: Angular Momentum, cross products
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Document PDF - 1.7 MB#
Page 1 to page 6

Torque and force; angular momentum and torque; torque and angular momentum of a conical pendulum; torque and angular acceleration; rigid body angular acceleration, with examples; torque due to gravity, with examples; conservation of angular momentum.

Instructor: Prof. Stanley Kowalski
Prior Knowledge: Lecture 22
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Document PDF - 1.6 MB#
Page 1 to page 1

Rotational dynamics examples, including particle on a string and spinning bicycle wheel.

Instructor: Prof. Stanley Kowalski
Prior Knowledge: Lecture 23
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Document PDF - 1.6 MB#
Page 1 to page 6

Work-energy theorem in rotational motion, with examples; angular impulse, with example; decomposition of displacement into translation and rotation; rolling motion of cylinders and spheres.

Instructor: Prof. Stanley Kowalski
Prior Knowledge: Lecture 23
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Document PDF - 1.3 MB#
Page 1 to page 5

Rolling motion of a rigid body, such as a cylinder or a sphere, with several examples; angular momentum and collisions, with example; gyroscope precession.

Instructor: Prof. Stanley Kowalski
Prior Knowledge: Lecture 24
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Document PDF - 1.2 MB#
Page 1 to page 10

Rotation about a fixed axis; definitions of angular velocity and angular acceleration; right-hand rule; rotational motion with constant angular acceleration; relationship between angular velocity, linear velocity, and acceleration, with example.

Instructor: Prof. Stanley Kowalski
Prior Knowledge: Lecture 17
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Document PDF - 1.2 MB#
Page 11 to page 16

Definition of rotational kinetic energy, with example; definition of moment of inertia for a rigid body; table of rotational inertia values for various objects; moment of inertia example.

Instructor: Prof. Stanley Kowalski
Prior Knowledge: Rigid Body Kinematics
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Document PDF
Page 1 to page 12

Parallel-axis theorem, with example; perpendicular-axis theorem, with examples; definition of angular momentum of a particle; definition of central forces; angular momentum of a particle moving in a straight line; angular momentum of a particle in uniform circular motion; angular momentum of a conical pendulum.

Instructor: Prof. Stanley Kowalski
Prior Knowledge: Lecture 21
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Document PDF
Page 13 to page 18

Relationship between forces and angular momentum; definition of the law of conservation of angular momentum; definition of torque; angular momentum and central forces, with examples.

Instructor: Prof. Stanley Kowalski
Prior Knowledge: Angular Momentum, Cross Products
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Document PDF
Page 1 to page 20

Torque and force; angular momentum and torque; torque and angular momentum of a conical pendulum; torque and angular acceleration; rigid body angular acceleration, with examples; torque due to gravity, with examples; conservation of angular momentum.

Instructor: Prof. Stanley Kowalski
Prior Knowledge: Lecture 22
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Document PDF
Page 1 to page 3

Rotational dynamics examples, including particle on a string and spinning bicycle wheel.

Instructor: Prof. Stanley Kowalski
Prior Knowledge: Lecture 23
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Document PDF
Page 4 to page 19

Work-energy theorem in rotational motion, with examples; angular impulse, with example; decomposition of displacement into translation and rotation; rolling motion of cylinders and spheres.

Instructor: Prof. Stanley Kowalski
Prior Knowledge: Lecture 23
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Document PDF
Page 1 to page 17

Rolling motion of a rigid body, such as a cylinder or a sphere, with several examples; angular momentum and collisions, with example; gyroscope precession.

Instructor: Prof. Stanley Kowalski
Prior Knowledge: Lecture 24
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Document PDF
Page 1 to page 2

Torque defined; conditions for rotational static equilibrium; torque and rotational dynamics; moment of inertia; parallel axis theorem.

Instructor: Dr. George Stephans
Prior Knowledge: Rotational Kinematics
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Document PDF
Page 1 to page 2

Checklist for solving torque problems; angular momentum defined, with equation; angular impulse defined, with equation.

Instructor: Dr. George Stephans
Prior Knowledge: Rotational Dynamics, Rotational Energy
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Document PDF
Page 1

Definition, with equation; moments of inertia for common shapes; angular momentum and moment of inertia.

Instructor: Dr. George Stephans
Prior Knowledge: Angular Momentum
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Document PDF#
Page 1

Equations for angular momentum of orbiting bodies; connection of angular momentum and rotational energy to equation of orbit.

Instructor: Dr. George Stephans
Prior Knowledge: Moment of Inertia
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Document PDF
Page 1

Analogy of a precessing gyroscope to uniform circular motion.

Instructor: Dr. George Stephans
Prior Knowledge: Angular Momentum, Circular Motion
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Document PDF#
Page 8 to page 19

Overview of translational and rotational dynamics of a rotating point mass; angular velocity and angular acceleration vectors for fixed axis rotation; angular momentum of a point particle using cross products; right hand rule; angular momentum for fixed axis rotation; torque and the time derivative of angular momentum for a point particle.

Instructors: Dr. Peter Dourmashkin, Prof. J. David Litster, Prof. David Pritchard, Prof. Bernd Surrow
Prior Knowledge: Rotational Dynamics
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Document PDF#
Page 20 to page 32

Angular momentum and torque for a system of particles; angular momentum of a rigid body for fixed axis rotation; conservation of angular momentum about a point; total angular momentum about a fixed point.

Instructors: Dr. Peter Dourmashkin, Prof. J. David Litster, Prof. David Pritchard, Prof. Bernd Surrow
Prior Knowledge: Angular Momentum of a Point Particle
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Document PDF#
Page 1 to page 13

Conditions under which momentum, energy, and angular momentum are conserved; total angular momentum about a fixed point; earth's orbital angular momentum about sun; earth's spin angular momentum; total angular momentum for Earth's motion about Sun.

Instructors: Dr. Peter Dourmashkin, Prof. J. David Litster, Prof. David Pritchard, Prof. Bernd Surrow
Prior Knowledge: Lecture 25
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Document PDF#
Page 1 to page 9

Angular momentum experiment setup and procedure.

Instructors: Dr. Peter Dourmashkin, Prof. J. David Litster, Prof. David Pritchard, Prof. Bernd Surrow
Prior Knowledge: Lecture 25
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Document PDF
Page 13 to page 26

Torque, rotational kinetic energy, moment of inertia, and rotational work defined; strategy for computing moment of inertia; translational and rotational kinematics/dynamics combined; Kepler's Law for conservation of angular momentum.

Instructors: Dr. Peter Dourmashkin, Prof. J. David Litster, Prof. David Pritchard, Prof. Bernd Surrow
Prior Knowledge: Lectures 24-27
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Practice Problems

Document PDF
Problem 1

Effect of tides on L and kinetic energy of earth-moon system; stable scenario for tidal system.

Instructor: Prof. Stanley Kowalski
Prior Knowledge: None
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Document PDF
Problem 1

Angular acceleration as a function of moment of inertia; motion of a rolling wheel.

Instructor: Dr. George Stephans
Prior Knowledge: None
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Document PDF
Problem 1 to problem 2

Linear and angular momentum of a rotating tennis ball; parallel axis theorem; collision between a rod and a small mass; impulse and angular momentum.

Instructor: Dr. George Stephans
Prior Knowledge: None
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Document PDF
Problem 1

Effects of changing the moment of inertia of a spinning object on angular velocity, angular momentum, and kinetic energy.

Instructor: Dr. George Stephans
Prior Knowledge: None
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Document PDF
Problem 1 to problem 2

Collisions between washers spinning on the same axis.

Instructor: Dr. George Stephans
Prior Knowledge: None
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Document PDF
Problem 1 to problem 2

Torque, angular velocity, and precession of gyroscopes.

Instructor: Dr. George Stephans
Prior Knowledge: None
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Document PDF
Problem 30(1)

Calculating the moment of inertia of a uniform circular disc about two parallel axes.

Instructors: Dr. Peter Dourmashkin, Prof. J. David Litster, Prof. David Pritchard, Prof. Bernd Surrow
Prior Knowledge: None
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Document PDF
Problem 30(2)

Frictional torque acting on a spinning uniform circular disc.

Instructors: Dr. Peter Dourmashkin, Prof. J. David Litster, Prof. David Pritchard, Prof. Bernd Surrow
Prior Knowledge: None
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Document PDF
Problem 1

Calculating the moment of inertia of a washer.

Instructors: Dr. Peter Dourmashkin, Prof. J. David Litster, Prof. David Pritchard, Prof. Bernd Surrow
Prior Knowledge: None
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Document PDF
Problem 2

Analysis of data collected in Experiment 8.

Instructors: Dr. Peter Dourmashkin, Prof. J. David Litster, Prof. David Pritchard, Prof. Bernd Surrow
Prior Knowledge: None
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Document PDF
Problem 4

Motion of a meteor approaching and just grazing the earth.

Instructors: Dr. Peter Dourmashkin, Prof. J. David Litster, Prof. David Pritchard, Prof. Bernd Surrow
Prior Knowledge: None
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Document PDF
Problem 5

Motion of a somersaulting diver.

Instructors: Dr. Peter Dourmashkin, Prof. J. David Litster, Prof. David Pritchard, Prof. Bernd Surrow
Prior Knowledge: None
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Document PDF
Problem 1

Analysis of a hydrogen atom modeled as an electron orbiting a proton.

Instructors: Dr. Peter Dourmashkin, Prof. J. David Litster, Prof. David Pritchard, Prof. Bernd Surrow
Prior Knowledge: None
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Document PDF
Problem 2

Analysis of data collected in Experiment 9.

Instructors: Dr. Peter Dourmashkin, Prof. J. David Litster, Prof. David Pritchard, Prof. Bernd Surrow
Prior Knowledge: None
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Exam Questions

Document PDF#
Problem 3

3-part problem; bullet hits side of cylinder; finding L, ω, and v of cylinder.

Instructor: Prof. Stanley Kowalski
Prior Knowledge: None
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Problem 9

Effect of a child jumping onto a merry-go-round.

Instructor: Dr. George Stephans
Prior Knowledge: None
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Problem 11

Collision of a bat with a baseball.

Instructor: Dr. George Stephans
Prior Knowledge: None
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Document PDF#
Problem 1

5-part problem; initial L and kinetic energy of washer, frictional torque, final ω of washers, average τ in collision.

Instructors: Dr. Peter Dourmashkin, Prof. Kate Scholberg
Prior Knowledge: None
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Document PDF#
Problem 3

Calculating ω and kinetic energy for bowling ball when it begins to roll; loss of KE.

Instructors: Dr. Peter Dourmashkin, Prof. Kate Scholberg
Prior Knowledge: None
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Problem 5

4-part problem; putty inelastically collides with stick; finding CM, p, ω, distance traveled in one revolution.

Instructors: Dr. Peter Dourmashkin, Prof. Kate Scholberg
Prior Knowledge: None
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Document PDF#
Problem 7

6-part problem; calculating α, ω, power exerted on merry-go-round; ω and kinetic energy after I changes.

Instructors: Dr. Peter Dourmashkin, Prof. Kate Scholberg
Prior Knowledge: None
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Document PDF
Problem 1d

Effect of a spinning figure skater pulling in her arms.

Instructors: Dr. Peter Dourmashkin, Prof. J. David Litster, Prof. David Pritchard, Prof. Bernd Surrow
Prior Knowledge: None
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Problem 6

Collision of rotating and stationary washers.

Instructors: Dr. Peter Dourmashkin, Prof. J. David Litster, Prof. David Pritchard, Prof. Bernd Surrow
Prior Knowledge: None
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Problem B3

Motion of a rotating merry-go-round, before and after children move to the center.

Instructors: Dr. Peter Dourmashkin, Prof. J. David Litster, Prof. David Pritchard, Prof. Bernd Surrow
Prior Knowledge: None
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Problem B7

Two masses connected by a rope wrapped around a pulley.

Instructors: Dr. Peter Dourmashkin, Prof. J. David Litster, Prof. David Pritchard, Prof. Bernd Surrow
Prior Knowledge: None
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Problem 1b

Kinematics and dynamics of a rotating tetherball.

Instructors: Dr. Peter Dourmashkin, Prof. J. David Litster, Prof. David Pritchard, Prof. Bernd Surrow
Prior Knowledge: None
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Problem 1d

Rotational energy of a spinning figure skater.

Instructors: Dr. Peter Dourmashkin, Prof. J. David Litster, Prof. David Pritchard, Prof. Bernd Surrow
Prior Knowledge: None
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Problem 3

Angular acceleration of a steel washer mounted on a cylindrical rotor.

Instructors: Dr. Peter Dourmashkin, Prof. J. David Litster, Prof. David Pritchard, Prof. Bernd Surrow
Prior Knowledge: None
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