Double Atwood's Machine

Prediction of motion of masses in a more complex pulley/mass assembly.

double atwoods machine

What it shows:  This compund Atwood's Machine demonstrates an old and interesting problem. The two small weights on the right side are not of equal mass — one is 100 g and the other...

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Atwood's Machine

Combinations of weights suspended over pulley to show that asymmetry causes acceleration.

atwood's machine

Image on the left, of a lightweight plastic pulley with balanced 50 g brass weights, and on the right, the pulley in motion as the unbalanced weights accelerate. 

Inertia of Rest

Concrete block smashed on lecturer's chest with sledge hammer.

What it shows:

The lecturer (or someone else) lies on a bed-of-nails without discomfort, thus demonstrating the concept of pressure, which is the force per unit area. For added drama the person is sandwiched between two beds of nails with the added weight of a cinder block on top. The cinder block can be broken with a sledge hammer.

How it works:

The forces (weight of the body, cinder block, etc.) are distributed over the total area of all the nail...

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Bosun's Chair

Block and tackle, or a simple pulley, attached to hall ceiling for lecturer to hoist self.

bosuns chair

Pulley Board

Upright board or Blackboard Mechanics with pulley combinations.

pulley board

Mechanical Linear Amplifier

What it shows:

One falling domino knocks down two, which in turn knock down three, etc. Use it to model cascade signaling.

How it works:

Twenty five rows of dominoes are set up in front of the first domino. Each successive row is comprised of one additional domino, e.g. the 2nd row has two, the 3rd row three, ... the 25th row has twenty five. A total of 325 dominoes get knocked down in a couple of seconds after the 1st one falls.

The action can be contrasted to a second board which has 11 rows of 30 tiles each, for a total of...

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Center of Mass

Irregular lamina with marked center-of-mass tossed in air.

What it shows:

The center of gravity fixed in (or outside) the object always orients itself with minimum potential energy on a vertical line below the support point. When an irregular shape is thrown into the air, it is seen to rotate about its marked center of gravity or center of mass (COM).

How it works:

We have several irregular lamina to suspend and/or throw in the air. They are (1) an amoeba shaped piece of masonite pegboard, (2) a cut-out map of the U.S. glued...

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Ball shot up from PASCO cart is caught by same; a puzzler to ponder if track is tilted and cart accelerates down (or decelerates up).


Uniform Acceleration

Glider acceleration by an inclined air track or by a falling weight/string attachment; large ballbearing rolling on PASCO track (with strings).

uniform acceleration

Time lapse image of a ping pong ball rolling down an inclined track. The bottom image has computer generated lines...

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