Gravitation, our latest simulations http://www.edumedia-sciences.com/ eduMedia, RSS feeds en quentin.thiaucourt@edumedia-sciences.com http://www.edumedia-sciences.com/media/logo.jpg Logo http://www.edumedia-sciences.com/ <![CDATA[Seasons 3D]]>

The Earth is tilted on its orbit. This causes an unequal amount of sunshine to fall in different parts of the planet during the course of a year, and this is responsible for the seasons. You can use this animation  to illustrate the  variations in the length of daylight,  and the seasons,  in the northern hemisphere.

The circles represented are:

  1. Arctic circle (66°N)
  2. 45°N latitude (Seattle, Toronto, Milan)
  3. Equator
  4. Antarctic circle (66°S)

The animation is not drawn to scale for either sizes or distances. Nor are the relative speeds of rotation and revolution accurately represented.

 

]]> <![CDATA[Gravitationnal force]]>
]]> <![CDATA[Tides]]>

Most of the time, there are two  tides each day. The understanding of this complex phenomenon is not simple and many great scientists (Aristotle, Galileo, Newton, Lagrange) attempted to attain that understanding. Gravitation is the force responsible for this phenomenon. The relative positions of the Moon, the Sun and the Earth explain the observed variations in this phenomenon.
Finally, the form of the littoral plays an important role in explaining the different amplitudes observed on the coasts.

]]> <![CDATA[Solar system]]>

Relative orbits for the planets of the solar system are shown. Their proportions are respected (except for the Sun) but not the scale ratio ! Pluto's orbit is elliptical and out of the ecliptic plane.

]]> <![CDATA[Free fall #3]]>

An object that falls through a vacuum experiences gravitational force (the weight of the object) . The downward acceleration is independent of the object’s mass as long as gravity is the only force acting, as shown if we create a vacuum inside the tank.  This is free fall.

]]> <![CDATA[Satellite]]>

Click and drag on  the screen to set the position and the initial velocity of the satellite.
Newton was the first to achieve the study of the dynamics of objects in space that we call now celestial mechanics. This animation allows one to use a single theory to explain short distance trajectories and orbital motion.

]]> <![CDATA[Tidal forces]]>

The two daily tides can only be explained in a dynamic study. The animation shows the tidal effect on the Moon and discusses Roche's limit, defined as the minimum distance to which a large satellite can approach its primary body without being torn apart by tidal forces.

 

]]> <![CDATA[Kepler's laws]]>
Kepler (1571 - 1630) announced his three famous laws of planetary motion in 1609:

  • Each planet moves in an elliptical orbit, with the sun at one focus of the ellipse.
  • A line from the sun to a given planet sweeps out equal areas in equal time.
  • The periods of the planets are proportional to the 3/2 power of the major axis length of their orbits.

    • This animation   illustrates the first two laws.
    ]]>         <![CDATA[Halley's comet]]>
    Comets are small bodies originating in the furthest reaches of the solar system, which orbit the sun in a highly elliptic path, thus obeying the laws of universal gravitation.
    Comets are a mixture of ice and meteoric matter. Near the sun, their volatile elements sublimate to form a cloud ending in a long tail which is always directed away from the sun.
    The path of Halley’s comet, with its 76 year period, is simulated here. You can click on the comet to drag it to different initial conditions, and so see other possible trajectories of such a body in a gravitational field.]]>         <![CDATA[Earth/Moon gravitational field]]>
    Gravitational fields (and force!) obey the principle of superposition. You can show that the field follows a spherical symmetry near the planets but the influence of the Earth  extends farther because of its superior mass (80 times Moon's mass).
    Notice the existence of a single point where the g field is equal to zero.
    Click on the screen to show or erase the field lines.
    This animation is not done to scale.
    ]]>