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The Physics of Pool
Resource ID#: 37787
Primary Type: Lesson Plan
This document was generated on CPALMS - www.cpalms.org
Direct Link: http://blossoms.mit.edu/videos/lessons/physics_pool
The objective of this lesson is to illustrate how a common everyday experience (such as playing
pool) can often provide a learning moment. In the example chosen, we use the game of pool to
help explain some key concepts of physics. One of these concepts is the conservation of linear
momentum since conservation laws play an extremely important role in many aspects of physics.
The idea that a certain property of a system is maintained before and after something happens is
quite central to many principles in physics and in the pool example, we concentrate on the
conservation of linear momentum. The latter half of the video looks at angular momentum and
friction, examining why certain objects roll, as opposed to slide. We do this by looking at how
striking a ball with a cue stick at different locations produces different effects.
Though not required, students who have been exposed to some physics would benefit most from
this video. In mathematically rigorous classes, students can concentrate on the details of vectors
and conservation of linear momentum.
No materials are required for this lesson, and it can be completed easily within a class period.
Subject(s): Science
Grade Level(s): 9, 10, 11, 12
Intended Audience: Educators
Suggested Technology: LCD Projector, Overhead Projector
Instructional Time: 50 Minute(s)
Freely Available: Yes
Keywords: Conservation of linear momentum, angular momentum, friction, vectors
Instructional Component Type(s): Lesson Plan, Problem-Solving
Task, Video/Audio/Animation, Tutorial, Student Center Activity
Instructional Design Framework(s): Direct Instruction, Demonstration, Predict-ExplainObserve-Explain, Confirmation Inquiry (Level 1), Cooperative Learning
Resource Collection: MIT BLOSSOMS
Additional Information/Instructions
By Author/Submitter
There are a few main ideas that we hope students take away from this video:
1. Conservation of linear momentum: Conservation laws play an extremely important role
in many aspects of physics. The idea that a certain property of a system is maintained
before and after something happens is quite central to many principles in physics. In the
pool example, we concentrate on the conservation of linear momentum. We illustrate
how when two objects collide (in this case, two billiard balls), the sum of their momenta
remains constant.We first illustrate this with two balls that collide and move in the same
direction, and then again when the two balls travel in different directions.For the latter
point, we illustrate the velocity (and momentum) really is a vector quantity. We conclude
the section with the idea that linear momentum is conserved for any "closed" system by
showing what happens when a collision occurs with a much larger object such as the pool
table.
2. Angular Momentum, Torque and Friction: The latter half of the video is aimed at trying
to look into why certain objects roll, as opposed to slide.We do this by looking at how
striking a ball with a cue stick at different locations produces different effects.
SOURCE AND ACCESS INFORMATION
Contributed by: Elizabeth Murray
Name of Author/Source: MIT BLOSSOMS
District/Organization of Contributor(s): Massachusettes Institute of Technology
Is this Resource freely Available? Yes
License: Attribution-NonCommercial 3.0 Unported
Related Standards
Name
SC.912.P.12.2:
Description
Analyze the motion of an object in terms of its position,
velocity, and acceleration (with respect to a frame of reference)
as functions of time.
Remarks/Examples:
Solve problems involving distance, velocity, speed, and
acceleration. Create and interpret graphs of 1-dimensional
motion, such as position versus time, distance versus time,
speed versus time, velocity versus time, and acceleration
versus time where acceleration is constant.
Florida Standards Connections: MAFS.912.N-VM.1.3 (+)
Solve problems involving velocity and other quantities that
can be represented by vectors.
Interpret and apply Newton's three laws of motion.
Remarks/Examples:
SC.912.P.12.3:
SC.912.P.12.4:
Explain that when the net force on an object is zero, no
acceleration occurs thus, a moving object continues to
move at a constant speed in the same direction, or, if at
rest, it remains at rest (Newton's first law). Explain that
when a net force is applied to an object its motion will
change, or accelerate (according to Newton's second law,
F = ma). Predict and explain how when one object exerts a
force on a second object, the second object always exerts a
force of equal magnitude but of opposite direction and
force back on the first: F1 on 2 = -F1 on 1 (Newton's third
law).
Describe how the gravitational force between two objects
depends on their masses and the distance between them.
Remarks/Examples:
Describe Newton's law of universal gravitation in terms of
the attraction between two objects, their masses, and the
inverse square of the distance between them.
Apply the law of conservation of linear momentum to
interactions, such as collisions between objects.
SC.912.P.12.5:
Remarks/Examples:
(e.g. elastic and completely inelastic collisions).
Qualitatively apply the concept of angular momentum.
Remarks/Examples:
SC.912.P.12.6:
Explain that angular momentum is rotational analogy to
linear momentum (e.g. Because angular momentum is
conserved, a change in the distribution of mass about the
axis of rotation will cause a change in the rotational speed
[ice skater spinning]).
Attached Resources
Video/Audio/Animation
Name
MIT BLOSSOMS - The
Physics of Boomerangs:
Description
This learning video explores the mysterious physics behind
boomerangs and other rapidly spinning objects. Students will
get to make and throw their own boomerangs between video
segments! A key idea presented is how torque causes the
precession of angular momentum. One class period is required
to complete this learning video, and the optimal prerequisites
are a familiarity with forces, Newton's laws, vectors and time
derivatives. Each student would need the following materials for
boomerang construction: cardboard (roughly the size of a
postcard), ruler, pencil/pen, scissors, protractor, and a stapler.