Astrophysical Principles - Gravitation

Mechanical model of Earth-Moon orbit around Sun.

What it shows:

A model to demonstrate the precession of the Moon's orbit relative to the ecliptic. It is useful for discussing the conditions necessary for the occurrence of an eclipse.

How it works:

A large...

Globe pivoted so north pole can precess.

What it shows:

Due to the oblateness of the Earth, the gravitational force between the Earth and the Sun sets up a couple which causes the Earth's axis of rotation to precess. An adapted globe shows what is meant by...

What it shows:

You can use a spherical blackboard for many things, including the teaching of geographical coordinates, as a model for a closed Universe, or simply as a mathematical shape.

In the non-Euclidean geometry of the sphere, a circle will have a...

Curved space segment for open universe geometry.

What it shows:

Whether the Universe continues to expand forever or will collapse back in upon itself depends upon the amount of matter it contains. For a density parameter Ω less than unity the Universe will...

1m diameter rubber sheet acts as curved space for ball bearing masses.

What it shows:

In general relativity, gravity is replaced by a curved space geometry, where the curvature is determined by the presence and distribution of matter. Objects move in...

Laser and plastic lens with curvature to simulate bending of light by massive object.

What it shows:

Gravitational lensing is caused by the bending of light rays by the gravitational field of an intervening object. The effect is seen with the Sun, but is...

Orbital motion simulated by ball rolling on wooden potential well.

What it shows:

Motion in a central potential is demonstrated by a ball rolling on a circular 1/r curved surface.

How it works:

The 1/r potential well simulates the gravitational potential...

Plane of pendulum oscillation appears to change due to rotation of Earth.

What it shows:

Due to the rotation of the Earth, the plane of oscillation of a pendulum will rotate with respect to the surface beneath it. We expect a rotation of about 10˚/hr at our...

Calculation of gravitational constant, with accompanying apparatus model.

What it shows

The gravitational attraction between lead spheres. The data from the demonstration can also be used to calculate the universal gravitational constant G.

A physical pendulum with two adjustable knife edges for an accurate determination of "g".

What It Shows

An important application of the pendulum is the determination of the value of the acceleration due to gravity. By adding a second knife-edge pivot and...