PIRA #

Demonstration Name

Abstract

1D10.20

Cycloid Generator

A large spool with a light bulb fastened to the circumference is rolled along the table. With and without the lights on.

1D10.30

Inversor

A mechanical device that transforms rotational motion into rectilinear motion.

1D10.40

Mounted Wheel

A bicycle wheel marked with a radial line turns about its axis.

1D10.55

Projected circular motion 

A Turn table with a ball that rotates with an arrow on top is projected on a screen by a arc lamp.

1D10.60

measuring angular velocity

Use an electronic strobe to measure the angular velocity of a fan blade or other rotating objects.

PIRA #

Demonstration Name

Abstract

1D15.10

ultrasonic detector and students

Have a student walk toward and away from a sonic ranger while observing plots of position, velocity, and acceleration on a projection of the Mac.

1D15.15

kick a moving ball

Kick a moving soccer ball on the floor or hit a moving croquet ball on the lecture bench with a mallet.

1D15.20

high road low road

Two objects start at the same velocity, one moves straight to the finish, the other traverses a valley. The problem: which wins?

1D15.30

catching the train

A ball accelerating down an incline catches and passes a ball moving at constant velocity on a horizontal track.

1D15.35

passing the train

A ball accelerates down an incline with a stripped rope moving at constant velocity in the background. The moment the ball has the same velocity as the rope is strikingly obvious. Repeat with the rope at a different constant velocity.

1D15.40

Galileo's circle

Several rods are mounted as cords of a large circle with one end of each rod top center. Beads released simultaneously at the top all reach the ends the rods at the same time.

1D15.45

brachistochrone track

Three tracks - straight line, parabola, and cycloid are mounted together. Triggers at each end control a timer. Details.

PIRA #

Demonstration Name

Abstract

1D40.10

throw objects

A slab of Styrofoam with lights placed at the center of gravity is tossed in the air.

1D40.11

center of mass disc

Throw a disc with uniform distribution and then offset the center of mass.

1D40.12

Hammer Toss

Mark the center of gravity of a hammer with a white spot. Throw it in the air and attach it to a hand drill to show it rotating smoothly.

1D40.13

throw objects

A bunch of junk is tied together with strings and thrown across the room.

1D40.15

loaded bolas

Three balls tied together and tossed in the air

1D40.20

spinning block

A large wood block has two holes with felt tipped pens, one on the center of mass. Place the block on a large sheet of paper and hit off center with a hammer.

1D40.22

air table center of mass

A weighted block glides across an air table.

1D40.25

photographing center of motion

Photographing the center of velocity of a variety of rigid bodies, using a high speed CCD camera.

1D40.30

throw the dumbbell

A dumbbell with unequal masses is thrown without rotation when the force is applied at the center of mass.

1D40.35

Earth-Moon system

Two unequal masses are fastened to the ends of a rigid bar. Spin the system about holes drilled in the bar at and off the center of mass.

1D40.50

air track pendulum glider

A double pendulum hangs from an air track cart with a mounted spot marking the center of mass. Set the system in oscillation and the spot will remain still or translate smoothly.

1D40.50

air track pendulum glider

A large glider with a pendulum on top of it.

1D40.50

air track pendulum glider

A double pendulum with equal masses are hung below a glider. A pendulums can swing together or not.

1D40.51

momentum pendulum

A pendulum support is free to move on rollers as the pendulum swings back and forth.

1D40.55

air track inchworm

The center of mass of two carts coupled with leaf springs is marked with a light or flag. Show oscillation about the center of mass or constant velocity of c of m.

1D40.60

satellite oscillation

Discussion of the LDEF satellite (30'x14'dia.) as an example where the distinction between the center of mass and center of gravity is important.

PIRA #

Demonstration Name

Abstract

1D50.10

ball on a string

Tie a lightweight ball to a sting and twirl around in a vertical circle.

1D50.10

ball on a string

Tie a whiffle ball to a sting and twirl around in a vertical circle.

1D50.15

arrow on a disk

Mount an arrow tangentially on the edge of a rotating disk.

1D50.20

whirligig

A large ball and a small ball fastened to opposite ends of a string which is threaded through a handle.

1D50.20

centripetal force apparatus

Use a glass tube for the holder and rubber stoppers for the masses.

1D50.20

whirligig

A large and small ball are on opposite sides of a string threaded through a handle.

1D50.20

whirligig

Two balls - 1 kg, 100 g - are attached to the ends of a 1 m string passing through a small hollow tube. Twirl a ball around your head.

1D50.20

ball on cord

A string with a rubber ball on one end passes through a plastic sleeve and weights are attached to a loop at the other end.

1D50.23

whirlygig

Apparatus Drawings Project No. 25: Construction of a low friction conical pendulum.

1D50.23

whirligig

The front axle of a bike is used for a whirligig support.

1D50.25

conical pendulum

A ceiling mounted bowling ball pendulum is used as a conical pendulum.

1D50.25

conical pendulum

A ball on a cord is rotated mechanically at a steady slow speed.

1D50.26

plane on string

A model plane flies around on a string defining a conical pendulum.

1D50.27

conical pendulum

Motorized triple bifilar coaxial conical pendula are used to demonstrate critical period.

1D50.28

conical pendulum

The main bearing of a conical pendulum is from a bicycle wheel axle. See also under whrilygig (AJP 30,221)

1D50.28

conical pendulum

The front wheel axle of a bike is used as a good bearing for a conical pendulum where the string tension is set by a counterweight. See AJP 31(1),58.

1D50.29

conical pendulum game

Swing a conical pendulum so it will strike a peg directly under the support on some swing other than the first.

1D50.30

canival ride model

A toy person is held on a vertical card at the edge of a turntable when the turntable is spun fast enough.

1D50.30

roundup

A toy person stands on the inside wall of a rotating cylinder.

1D50.37

swinging up a weight

An arrangement whereby a swinging 500 g weight picks up a 1000 g weight.

1D50.40

pail of water

Swing a bucket of water in a verticle circle over your head.

1D50.40

pail of water, pail of nails

Swing a bucket of water in a vertical circle over your head. If nails are used, they can be heard dropping away from the bottom of the can.

1D50.40

pail of water

A pail of water is whirled around in a vertical circle.

1D50.40

pail of water

Swing a bucket of water over your head.

1D50.40

whirling bucket of water

Rotate a bucket of water in a vertical circle.

1D50.45

penny on the coathanger

Place a penny on an elongated coat hanger and rotate around your finger.

1D50.45

penny on the coathanger

A penny is balanced on the hook of a coat hanger. The coat hanger is twirled around your finger and the penny doesn't fly off.

1D50.45

penny on the coathanger

The wire coat hanger is whirled about the vertical plane by the hook without dislodging the dime on the middle of the lower bar.

1D50.45

penny on the coathanger

Place a coin on the coat hanger and rotate it about the finger.

1D50.45

coin on coat hanger

A coin is placed on the flat of the hook of an elongated coat hanger and twirled around.

1D50.48

balls on a propeller

Balls sit in cups mounted on a swinging arm at .5 and 1.0 m. Calculate the period necessary to keep the ball in the outer cup and swing it around in time to a metronome.

1D50.50

Welch centripetal force

The angular velocity and mass needed to stretch a spring a certain distance are compared.

1D50.50

Welch centripetal force review

Uses no motor, self contained static force measurement.

1D50.50

Welch centripetal force

The angular velocity and mass needed to stretch a spring a certain distance are compared.

1D50.51

Welch centripetal force modification

Two modifications to the apparatus.

1D50.51

Welch centripetal force

A modification to improve the Sargent-Welch 9030 centripetal force apparatus.

1D50.51

Welch centripetal force modification

Improvements to the Welch centripetal force apparatus.

1D50.53

variable centripetal force

A new design for the apparatus that allows any two of the three variables of mass, angular velocity, and distance to be kept constant.

1D50.53

Cenco centripetal force

A relay starts the counter and clock so three hands are not needed when using the Cenco 74470 apparatus.

1D50.53

Cenco centripetal force

Lab apparatus used as a demonstration.

1D50.54

Cenco centripetal force modification

Replace the screw adjustment for the fixed end of the spring with a movable plate.

1D50.55

hand rotator

Two 2000 g spring balances are mounted on a rotator. Equal masses are attached to each and readings are taken at some rotational velocity.

1D50.60

banked track

A steel ball rolled down an incline into a funnel reaches an equilibrium level where it revolves in a horizontal plane.

1D50.62

ball in a megaphone

Throw a ball into a megaphone and it turns around and comes out the wide end.

1D50.65

banked track

A turntable can be rotated at various angular frequencies. Objects can be placed at different radii. A small platform can be attached which will swing out to the correct slope for any angular velocity. A device for measuring force is also shown.

1D50.69

puzzle

Two balls in a box must be caught in end pockets simultaneously.

1D50.70

rolling chain

A loop of chain is spun up on a disc and released to roll down the lecture bench as a rigid hoop.

1D50.70

rolling chain

A flexible chain is spun on a motorized pulley. When it is released, it maintains rigidity as it rolls down the lecture bench.

1D50.70

rolling chain

A loop of chain is brought up to speed on a motorized disc and when released rolls down the lecture bench over obstacles.

1D50.70

rolling chain

A loop of chain spun on a wheel and forced off remains rigid for some time.

1D50.70

spinning chain

Spin a flexible chain rapidly enough that it acts as a solid object.

PIRA #

Demonstration Name

Abstract

1D52.10

flattening earth

A hand crank spins a globe made of flexible brass hoops.

1D52.10

flattening Earth

Flexible hoops flatten when spun on a hand crank rotator.

1D52.10

centrifuge hoops

A flexible hoop becomes oblate as it is rotated.

1D52.11

flattening Earth

Spin deformable balls. A clay/glycerin ball will burst, a sponge rubber ball will deform greatly.

1D52.17

empty jug by swirling

A jug will empty faster when swirled.

1D52.20

water parabola

A rectangular plexiglass box partially filled with colored water is rotated. The parabolic shape is clearly seen.

1D52.20

water parabola

A flat sided tank half full of water is rotated on a platform.

1D52.20

water parabola

A small self strobed rotating plexiglass container is used to project the water parabola.

1D52.20

water parabola

A glass cylinder half filled with colored water is spun on a rotating table.

1D52.20

parabolid of revolution

A cylindrical container with some water is rotated at a constant speed.

1D52.21

rotation water troughs

Two water containers are mounted on a rotating table. A rectangular container mounted radially shows half a parabola, and another formed in an arc of constant radius stays level.

1D52.23

rotating manometer

Tubing constructed in an "E" shape on its back is partly filled with water and rotated.

1D52.24

rotating manometer

A U shaped manometer is mounted with one of its arms coincident with the axis of a rotating table.

1D52.26

project mercury parabola

Spin a dish of mercury and image a light bulb on the ceiling.

1D52.30

balls in water sentrifuge

Cork and steel balls are spun in a curved tube filled with water.

1D52.30

balls in water centrifuge

Wood balls in two curved tubes, air and water filled, are rotated.

1D52.30

balls in water centrifuge

Spin a bent glass tube filled with water that contains two wood or steel balls.

1D52.30

balls in water centrifuge

Spin a bent glass tube filled with water containing cork and aluminum balls.

1D52.30

balls in water centrifuge

A glass bowl containing water, a steel ball, a cork ball is spun.

1D52.30

corks in water centrifuge

Spin a semicircular tube filled with water containing two corks.

1D52.31

inertial pressure gradient

A bubble in a tube goes to the center when whirled in a horizontal circle.

1D52.31

centrifuge

A long thin tube containing a wood plug is rotated horizontal while either filled with water or empty.

1D52.31

balls in water centrifuge

A long thin tube containing a brass ball, ping pong ball, and water is rotated.

1D52.33

cork and ball rotating in water

One cork is tied to the bottom, one ball is tied to the top of two cylinders full of water at the ends of a rotating bar.

1D52.33

rotating corks in water

Corks tied to the bottom of two jars full of water are first translated on a cart and then put on a pivot and rotated about the center.

1D52.34

car picture

A picture taken from inside a car of a candle, CO2 balloon, H2 balloon as the car is driven in uniform circular motion.

1D52.35

mercury/water centrifuge

A globe with water and mercury on a hand crank rotator.

1D52.35

mercury/water centrifuge

A spherical glass bowl is spun and mercury forms a equatorial band with water above and below.

1D52.35

water and mercury centrifuge

Water and mercury spin in a glass sphere.

1D52.36

centrifuge

Diagram for building a projection cell centrifuge.

1D52.37

centrifuge

A hand cranked test tube centrifuge.

1D52.38

the full skirt

Spin a doll with a full skirt or kilt. Cheap thrills.

1D52.40

rotating candle

A candle is placed on a turntable and covered with a large plexiglass hemisphere.

1D52.40

rotating candle

Make the rotating candle out of meter sticks and candles.

1D52.40

central pressure gradients

A candle rotates in a chimney on a turntable.

1D52.40

rotating candle

A lighted candle in a chimney goes around on a dry ice puck string attached by a string to a pivot.

1D52.40

rotating candle

A lighted candle in a chimney lamp on a rotating table will point to the center.

1D52.40

rotating candle

Lighted candles in chimneys are rotated about the center of mass.

1D52.45

geotropsim

Grow corn or wheat on a rotating turntable two weeks before class.

1D52.50

paper saw

A 6" paper disc placed on a dremmel tool cuts another sheet of paper.

1D52.50

paper saw

Typewriter paper will cut through other paper, Bristol board will cut through wood when spun at high speeds.

1D52.60

rubber wheel

A sponge rubber wheel with one spoke cut is rotated at high speed and viewed under stroboscopic light.

1D52.61

rotating rubber wheel

A rubber wheel stretches to a larger radius when spun.

1D52.70

wobbling Christmas tree toy

A Lagrangian-effective potential solution explaining the behavior of this toy.

1D52.90

centripetal-centrifugal discussion

A final (?) note on the topic from the editor.