## Planetary motion lab

The gravitational constant, symbolized G, is a physical constant that appears in the equation for Newton’s law of gravitation. Sir Isaac Newton (1642-1727), the English mathematician, quantified the behavior of the force of gravity. He noticed that the gravitational force between two objects is proportional to the product of their masses, and inversely proportional to the square of the distance between their centers. According to Newton’s law , given any two objects having mass m1 and m2 (in kilograms) whose centers of mass are separated by a distance x (in meters), there exists an attractive gravitational force F (in units of Newtons) between the objects, such that:

Formula of Newton’s law of gravitation

Image: Formula of Newton’s Law of Gravitation.

The value of G in this equation is approximately equal to 6.67 x 10-11 Newton meters squared per kilogram squared (N x m2 x kg-2). This constant is uniform throughout the Solar System, and apparently throughout our galaxy and other galaxies in its vicinity.

Solar System Simulator:

With this orbit simulator, you can set initial positions, velocities, and masses of 2, 3, or 4 bodies (planets), and then see them orbit each other. There are also 11 preset scenarios. Try at least a few of them, or if you have the time and interest try all

. The instructions said to position body 3 at 0, 200 and to adjust the y velocity to get a circular orbit. This will not work. They should have said to position body 3 at 200, 0. This did not seem to be a problem for most of you. Either you realized the position should be 200, 0 or you adjusted the x velocity to get a circle, which would work.

Solar system simulator

https://phet.colorado.edu/sims/my-solar-system/my-solar-system_en.html