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.

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.