Museum of Science's Motion: Motion: Speed, Velocity and Acceleration ...
Acceleration ‒ a measure of the change in the velocity of an object over a period.
Educator Guide: Motion: Speed, Velocity and Acceleration This document is a resource for teachers whose classes are attending the Museum of Science’s Motion: Motion: Speed, Velocity and Acceleration presentation. The information in this document may be used as a classroom resource and/or as background information for the teacher concerning the subject of motion and physics.
Table of Contents:
Vocabulary List……………………………………………………………………………2 Classroom Materials……………………………………………………….....................5 Activity Description..……………………………………..…………………………..…...7 Video Description..………………………………………………………..……………...8 PowerPoint Description…………………………………………………..………………9
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Vocabulary List This is a list of common physics terms that teachers may wish to be familiar with for the Motion: Speed, Velocity, and Acceleration program. This list is also a suggestion of vocabulary for students attending the program to learn, though prior study of these words is not required for student participation. Acceleration – a measure of the change in the velocity of an object over a period of time. The change in velocity can be observed as a change in speed or a change in direction, such as 10 m/s2 east. a = ∆v/∆t Angular Momentum – a concept used to describe the spinning momentum of an object. Momentum is a vector quantity and must be expressed with both a magnitude and a direction. Ex. 10 kgm2/s clockwise. Conservation of Momentum – a law that states that in the absence of a net external force, the momentum of an object or system of objects is conserved (remains unchanged). Conservation of Angular Momentum – a law that states that in the absence of a net external force, the angular momentum of an object or system of objects in rotation is conserved (remains unchanged).
Impulse – the product of force and the time interval during which the force acts. Impulse produces a change in momentum. Impulse = F∆t = ∆(mv) Inertia – the property of an object to resist a change in its motion. Mass is a measure of an object’s inertia. Mass – a measure of how much matter an object has. Mass can also be explained as a measure of the inertia of a material object; the more mass an object has, the greater its inertia or the more it will resist a change in its motion.
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Measurement – Standards for Some Common Measurements used in Physics Measurement Speed Velocity Acceleration Mass Force Momentum Rotational Velocity Angular Momentum
SI units m/s m/s m/s2 kg N (kgm/s2) kgm/s radians/s kgm2/s
English units ft/s ft/s ft/s2 slug lb none none none
Momentum – a concept used to describe the tendency for objects in motion to resist changes in that motion. Momentum is the product of the mass and velocity of an object. This relationship is expressed by the formula: p = mv Momentum is a vector quantity and must be expressed with both a magnitude and a direction, such as 10 kgm/s east. Newton’s First Law (The Law of Inertia) – An object will remain at rest or in uniform motion in a straight line unless compelled to change its state by the action of an unbalanced force (net force). In other words, objects at rest tend to stay at rest and objects in motion tend to stay in motion. Newton’s Second Law – This law describes the relationship of acceleration to force and inertia in a way that can be expressed by the formula: Fnet = ma As a result of this relationship, an object will be accelerated in the direction of the net force in an amount directly proportional to the amount of that net force. Newton’s Third Law – Forces come in pairs and this law describes how these pairs of forces act on an object. The law states that “whenever one object exerts a force on a second object, the second object exerts an equal and opposite force on the first.” In other words, in any interaction there is an action and reaction pair of
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forces that are equal in magnitude and opposite in direction. Neither force exists without the other. Rotational Inertia – the property of an object to resist changes in its rotation. Rotational inertia is dependant upon an object’s mass and the distribution of that mass with respect to the object’s axis of rotation. Rotational Velocity (Angular Velocity) – a measure of how fast an object is rotating (rotational speed) and the direction of its axis of rotation or revolution, such as 10 rad/s clockwise. Scalar – a quantity that can be described using only magnitude. Speed, mass, and volume are all scalar quantities. Speed – a measure of how fast an object moves. Speed measures the distance an object travels over a period of time, such as 10 m/s. s = ∆d/∆t Vector – any quantity that must be described as having both magnitude and direction. Force, velocity, acceleration, momentum, torque, and angular momntum are all vector quantities. Velocity – a measure of how fast an object moves (speed) and the direction of its motion, such as 10 m/s east. v = ∆d/∆t
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Classroom Materials Below are some suggestions for books, videos, and websites to help students increase their understanding of physics and motion.
Books The Cartoon Guide to Physics by Larry Gonick and Art Huffman. Harper Perennial Books. 1991. The Art of the Catapult by William Gurstelle. Chicago Review Press. 2004. The Handy Physics Answer Book by P. Erik Gundersen. Visible Ink Press. 1999.
Articles Laying Siege to Parabolic Understanding by John W. Rick. Mathematic Teaching in the Middle School. Vol. 15, No. 4. November 2009. pp. 198-204. Some great ideas on using the trebuchet to explore mathematical concepts
Videos Secrets of Lost Empires II – Medieval Siege (DVD). PBS NOVA. 2000. Episode website: http://www.pbs.org/wgbh/nova/teachers/programs/27ms_sle2treb.html
Links Yankee Siege –World Champion pumpkin throwing trebuchet located in Greenfield, NH. The site has lots of great information on the physics of the trebuchet as well as some amazing videos of their 55ft tall machine in action – http://www.yankeesiege.com/
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PBS NOVA – A wide variety of resources on the engineering and physics behind different siege engines – http://www.pbs.org/wgbh/nova/lostempires/trebuchet/ http://www.teachersdomain.org/resource/hew06.sci.phys.maf.trebuchet/ Shoot the Monkey Interactive – Manipulate the velocity and angle of your projectile along with other variables to see if you can hit the target just like we do in the assembly – http://interactagram.com/physics/gravity/monkeyShooter/ Trebuchet.com – A resource for building your own trebuchet in the classroom. They have many kits and plans available for trebuchets and other types of siege engines – http://www.trebuchet.com/ The Science Channel: Punkin Chunkin – A website featuring the modern siege engines that compete each year in the world championship pumpkin throwing competition in Delaware. Some of these machines can throw a pumpkin almost a mile! The world championship throw with a trebuchet is by New England’s own Yankee Seige team (link above) – http://science.discovery.com/tv/punkin-chunkin/ Storm the Castle – This site is filled with lots of plans and ideas for building your own trebuchet for the classroom or for inspiring students who wish to build their own siege engines – http://www.stormthecastle.com/trebuchet/index.htm
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Activity Descriptions See the “Documents” section on the website to download this activity. Tennis Ball Throwers Using a simple dog toy designed for throwing tennis balls, students can explore how changing a variety of variables affects the motion of a projectile.
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Video Descriptions See the “Media” section on the website to download this video.
Yankee Siege This video showcases the world Punkin Chunkin champion: Yankee Siege. This 55 foot tall trebuchet can throw an 8 lb. pumpkin over 2000 feet. (www.yankeesiege.com)
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PowerPoint Description See the “Documents” section of the website to download the PDF of this PowerPoint.
Vocabulary and Motion Laws This PowerPoint mathematically defines important motions terms such as speed, velocity, acceleration, and momentum and also details Newton’s 3 Laws of Motion.
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