What it shows: The intensity of light from a point source decreases as 1/r2, where r is the distance from the source.
How it works: For the point light source, we use a 1500 watt clear light bulb. The detector is a small solar panel.1 The output current is directly proportional to the intensity of the light falling on the panel and the current is displayed on an analog milliameter. (The current can also be measured by a digital meter or computer.) Measured...
A realistic model of the forces in the erector spinae muscles that support the back when bent over.
What it Shows:
This is an analysis of the tensions in muscles and forces on joints as an application of torques in static equilibrium situations. The muscles involved in supporting the human torso in a stooped position are realistically modeled, and the extraordinary large forces calculated and demonstrated.
How it Works:
When bending over into a stooped position, the principal muscles which support the back are the erector...
Radio controlled car moves one way while road moves the other.
What it shows:
We tell our students that, when a car drives down the road, the road and the Earth move in the opposite direction, albeit imperceptibly. This demonstration is a realization of that concept, made possible (and perceptible) by the fact that the road is not attached to the Earth.
Currently we provide two different versions of this experiment. One version uses balls rolling down a long, inclined track (roughly 2 meters), and the other version uses balls that swing on a pendulum.
Blow up a long cylindrical balloon and it inflates according to Laplace's law. Arteries, which also need to be flexible, are designed to fight against the kind of aneurysms seen in inflating rubber balloons.
A rigid rod executes simple harmonic motion about an adjustable pivot point.
What It Shows
The period of a physical pendulum is measured and compared to theory. The pivot point, and thus the period, is adjustable along the length of the pendulum making it possible to demonstrate that there is a pivot point where the period is a minimum (stationary point).
How It Works
The physical pendulum is a 1/2" diameter × 100cm long brass rod. A collar with a "knife edge" can be fixed anywhere along the length of the pendulum and serves as the pivot point. The period...