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||1K10.20||Ladder Against a Wall||Set a model ladder against a box and move a weight up a rung at a time.|| ||1K10.20||[:Ladder Against a Wall]||A model ladder is set to lean against a wall. A weight is then moved up one rung at a time.||
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||1K10.30||[:Walking the Spool]||Pull on a cord wrapped around the axle of a large spool. The spool can be made to go forward or backward depending on the angle of torque. See [http://physicslearning.colorado.edu/PIRA/Sutton/PARTI.pdf#pagemode=none&page=1 Sutton M-24].|| ||1K10.30||[:Walking the Spool]||Pull on a cord wrapped around the axle of a large spool. The spool can be made to go forward or backward depending on the relative angle of applied torque. See [http://physicslearning.colorado.edu/PIRA/Sutton/PARTI.pdf#pagemode=none&page=1 Sutton M-24].||

[:PiraScheme#Mechanics: Table of Mechanics]

[:RigidBodies: Mechanics (1J): Statistics of Rigid Bodies]

[:Gravity: Mechanics (1L): Gravity]

[:Demonstrations:Lecture Demonstrations]

Applications of Newton's Laws

PIRA classification 1K

34 Demonstrations listed of which 20 are grayed out

Grayed out demonstrations are not available or within our archive and are under consideration to be added.


1K10. Dynamic Torque


Demonstration Name



Tipping Block

A spring scale is used to show the least force required to overturn large wooden block.


Tipping Block

Show the force necessary to tip over trapezoidal and weighted rectangular blocks. The students are surprised to discover the force needed is not related to the position of the center of mass. See [http://scitation.aip.org/getpdf/servlet/GetPDFServlet?filetype=pdf&id=PHTEAH000022000008000538000001&idtype=cvips&doi=10.1119/1.2341657&prog=normal TPT 22(8), 538].


[:Ladder Against a Wall]

A model ladder is set to lean against a wall. A weight is then moved up one rung at a time.


Forces on a Ladder - Full Scale

Wheels are attached to the top of a ladder and the bottom slides on the floor. Climb up the ladder and fall down. See [http://physicslearning.colorado.edu/PIRA/Sutton/PARTI.pdf#pagemode=none&page=1 Sutton M-30].


[:Walking the Spool]

Pull on a cord wrapped around the axle of a large spool. The spool can be made to go forward or backward depending on the relative angle of applied torque. See [http://physicslearning.colorado.edu/PIRA/Sutton/PARTI.pdf#pagemode=none&page=1 Sutton M-24].


Walking the Spool x three

Three rolling spools: the outer discs ride on rails and the center section with the string is larger, smaller, and the same size as the outer discs allowing one to always pull horizontally.


Pull the Bike Pedal

Lock the front wheel, remove the brake, add training wheels, and pull backwards on the pedal in the down position. Pulling backward on a pedal (in the down position) of a brake-less bike will cause the bike to go back unless the length of the pedal crank is increased. See [http://physicslearning.colorado.edu/PIRA/Sutton/PARTI.pdf#pagemode=none&page=1 Sutton M-25].


Traction Force Roller

Pull on a string wrapped around the circumference of a cylinder on a roller cart. Pull on a yoke attached to the axle of the same cylinder on the roller cart. See [http://scitation.aip.org/getpdf/servlet/GetPDFServlet?filetype=pdf&id=AJPIAS00003400000300xxix000001&idtype=cvips&doi=10.1119/1.1972925&prog=normal AJP 34(3),xxix].


Extended Traction Force

A string wound around a cylinder, hoop, and spool is pulled while the objects are on a roller cart and the reaction force direction is surprising. [http://scitation.aip.org/getpdf/servlet/GetPDFServlet?filetype=pdf&id=PHTEAH000028000009000600000001&idtype=cvips&doi=10.1119/1.2343174&prog=normal TPT 28(9), 600].


Rolling uphill

A loaded disc is put on an inclined plane so it rolls uphill or rolls to the edge of the lecture bench and back.


Teaching Couples

Start with two index fingers rotating a meter stick about the center of mass, use it to go into couples.


Free Vector

A strong magnet on a counterbalanced cork always rotates about the center of mass no matter where the magnet is placed. See [http://physicslearning.colorado.edu/PIRA/Sutton/PARTI.pdf#pagemode=none&page=1 Sutton M-20].



An arrangement to apply equal forces to opposite sides of a pulley mounted on a dry ice supported steel bar.


Air Jet Couple

Air from a balloon is released through two nozzles offset from the center of mass. The assembly is free to rotate on a block of dry ice. See [http://scitation.aip.org/getpdf/servlet/GetPDFServlet?filetype=pdf&id=AJPIAS000028000001000076000002&idtype=cvips&doi=10.1119/1.1934981&prog=normal AJP 28(1), 76].


One Person Teeter Totter

One person sits on one side of an unbalanced teeter-totter but is able to bring it into equilibrium by applying a torque to a bar placed across his shoulders. See [http://scitation.aip.org/getpdf/servlet/GetPDFServlet?filetype=pdf&id=PHTEAH000005000003000138000001&idtype=cvips&doi=10.1119/1.2351115&prog=normal TPT 5(3), 138].


1K20. Friction


Demonstration Name



Washboard Friction Model

Two plants with a zig-zag pattern cut in the faces. Slide them past each other.


Friction Blocks

Pull blocks with different surfaces across the lecture bench with a spring scale.


Sliding Friction Machine

A spring scale is attached to an object on a rotating table. See [http://scitation.aip.org/getpdf/servlet/GetPDFServlet?filetype=pdf&id=AJPIAS000033000002000161000001&idtype=cvips&doi=10.1119/1.1971287&prog=normal AJP 33(2),161].


Weight Dependence of Friction

Pull a friction block with a spring scale, place a second block of equal weight on top of the first and repeat.


Sliding Block

A loaded cart rolls down an incline and hits a barrier. The load continues sliding on a second incline until it stops. The mass on the slider is varied to show stopping distance independent of mass.


Area Dependence of Friction

A friction block is slid across the table with a spring scale measuring the friction force. One side has a an area ten times larger than the other, shaped like a plank with two small blocks attached to one face. See [http://physicslearning.colorado.edu/PIRA/Sutton/PARTI.pdf#pagemode=none&page=1 Sutton M-49].


Area Dependence of Friction

A 2X12 is pulled along the bench top while resting on either the narrow or wide face.


Phone Book Friction


[:Static vs. Kinetic Friction]

A spring scale attached to a block is used to pull on the block until it begins to move. The force registering on the scale is largest just before the block begins to move demonstrating that static friction is greater than kinetic friction.


[:Angle of Repose]

An inclined plane is raised until a block starts to slide.


[:Friction on an Adjustable Inclined Plane]

A weighted wood block is placed on an inclined plane with upward tension provided by a counterweight attached by a string running over a pulley. The tension is just enough to balance the weight so that the force due to static friction is just enough to prevent slipping. A nudge then triggers the block to slide.


Tire Friction

The automobile tire is a misleading example of static and sliding friction. See [http://scitation.aip.org/getpdf/servlet/GetPDFServlet?filetype=pdf&id=AJPIAS000046000008000858000001&idtype=cvips&doi=10.1119/1.11406&prog=normal AJP 46(8),858].


Stability and Breaking of Cars

A toy car slides down an incline with either front or rear wheels locked.


Friction Roller

A cylindrical roller is pulled or slid across the lecture bench with a spring scale.


Sliding Chain

Hang a chain over the edge of the table until the weight of the chain makes it slide.


Falling Flask Capstan

Attach a 4 liter r.b. flask at one end of a sting, attach a ball to the other end and drape the flask over a horizontal rod 4' high. Let go of the ball.


Friction Pendulum

A ball is suspended by a loop of string over a slowly turning horizontal wooden bar. A large amplitude results. See [http://physicslearning.colorado.edu/PIRA/Sutton/PARTI.pdf#pagemode=none&page=1 Sutton M-54].


Tree Climbing

A string is looped down through a tube, which is attached to a board, and around a nail which is not, and back up through another tube, which is attached to the same board. Pulling the ends of the string up and down results in the entire apparatus climbing up the string.


Air Track Friction

Show there is little friction on an air track.


1K30. Pressure


Demonstration Name



[:BedofNails:Bed of Nails]

A 2′ by 4.5′ bed of nails is made up of 80d nails placed in a 1" grid. The bed contains 1375 aluminum nails which have been leveled and dulled. A second bed of nails (1.5′ x 2.5′) made up of 425 aluminum nails placed in a 1" grid can be placed on top of the person lying on the larger bed of nails. For extra excitement, break a cinder block that is placed, centered and stable, on top of the small bed of nails.


Pop the Balloon

A balloon can be pressed into varying densities of nails by varying amounts of weight.



fw: AppNewtonsLaws (last edited 2018-07-18 16:53:21 by srnarf)