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Scantling and Ball

Ball rolling down tilted trough in oscillatory fashion yields acceleration. Also known as Galileo's Inclined Plane).

scantling and ballWhat It Shows

An ingenious experiment to measure acceleration due to gravity first performed by Galileo.

How It Works...

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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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Pulley Board

Upright board or Blackboard Mechanics with pulley combinations.

pulley board

Jaw Models

Cardboard animal jaws as examples of levers.

What it shows:

The biting force of an animal depends upon the magnitude, direction and point of application of forces exerted by the jaw muscles. A mammalian jaw exerts a greater force than does a reptilian jaw despite a more delicate joint structure, because evolution has improved the physics of eating.

How it works:

The demonstration consists of two dimensional cardboard models of reptilian and mammalian lower jaws (see figure 1). Both are about 30cm in length. They are pivoted...

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Fakir Physics

The concept of pressure is demonstrated by lying on a bed of nails.

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.

figure 1: A supermarket tabloid reports on how macho man pulls off this stunt.
...

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Friction Blocks

Selection of blocks that slide down a variable-angle inclined plane to demonstrate the various aspects of friction.

What it shows:

There are actually three (or more) demonstrations under the wing of this title: (1) A block or box is placed on an adjustable inclined plane which can be raised until the block slides. The tangent of the angle then gives the coefficient of friction between the surfaces. (2) The difference between dynamic and static friction may be demonstrated. A large dial spring balance is used to determine the forces required to drag a box on...

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Three-Legged Table

Triangular table supported by platform scales.

What it shows:

This is a two-dimensional version of the Loaded Beam demonstration.

How it works:

An equilateral triangular-shaped table is supported at each corner by a platform scale (same type as in "Loaded Beam"). One of our large (14.5 kg = 32 lb) weights is placed on the table. The scale readings vary with the position of the weight. The procedure to be followed in this demonstration...

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Vector Arrows

Wooden arrow vectors, hand held or mountable.

What It Shows:

Various length and color, wooden arrow vectors can be hand-held, placed (magnetically) on the blackboard, or stuck into a wooden block to define a coordinate system. Small vector blocks can be used as body axes or to visualize coordinate transformations.

...

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Stack of Blocks

A dozen blocks are stacked on top of each other over the edge of the table seemingly defying gravity.

What it shows:

N objects of unit length can be stacked on top of each other so that the top object sticks out over the edge of the lecture bench by a distance equal to 1

1/2 + 1/4 + 1/6 + 1/8 + ... + 1/(2N)

For N approaching ∞, the diverging infinite sum suggests that the top of the pile can stick out an infinite distance. In actuality the divergence is slow, 2 and our more practical stack of a dozen 2 × 4 "blocks" can...

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Vector Sum of Forces

Magnetic blackboard mechanics with spring balances and weights.

What it shows:

Solve a problem in composition of concurrent forces by graphical or trigonometric means.

How it works:

The blackboard mechanics set1 includes apparatus to demonstrate most of the common laws of statics and some dynamics. The pieces of apparatus are held on the blackboard by magnets and, although not large, are fairly visible in the lecture hall. A booklet with a few dozen suggested demonstration experiments is included in the set.
...

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Leaning Ladder

Small ladder against wall with variable load and inclination.

What it shows: 

A small ladder is leaned against a vertical wall. A weight can be moved up succeeding steps to find when the ladder will slip and fall down. The forces holding the ladder in equilibrium are in consideration here.

How it works: 

A short (4 foot) step-ladder leans against the wall. The reaction of the wall may be considered horizontal, tangential friction being negligible (the edge of the ladder is covered with a sheet of...

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Irregular Lamina

center of gravity - center of mass - equilibrium

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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Shoot-n-Drop

Ball shot horizontally, one dropped vertically; both hit the ground at the same time.

What it shows:

The horizontal and vertical motions of a projectile are independent of each other. So two objects falling under the influence of gravity from the same height will reach the ground simultaneously, regardless of their horizontal velocities.

...
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