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The information below is intended to provide introductory material for elementary students and further material for high school students.

Please keep in mind that not all demonstrations are presented at each show, and each topic may not be covered.



  • At the Earth's surface, all objects experience a downward force due to gravity. This force depends on the object's mass: the greater the mass, the greater the force.

    All massive objects are attracted to all other massive objects. This force is known as the gravitational force. At the Earth's surface, the mass of the Earth is attracting the mass of all other objects with the gravitational force. The more massive an object is, the more force is exerted on it by the Earth. We know that this is true because a very massive object, such as a bowling ball, is much more difficult to lift from the ground than a less massive object, such as a tennis ball. The gravitational force is greater on the bowling ball than on the tennis ball.

  • More Specifically

  • At the Earth's surface, Fg = mg, where Fg = force due to gravity, m = mass, and g = gravitational acceleration.

    At the Earth's surface, the acceleration due to gravity is the same for all objects. This value is called the gravitational acceleration, g. This value is constant for a given altitude on the Earth's surface. This constant varies very little for most of Earth's altitudes. As can be seen from the formula, the force due to gravity is directly proportional to the mass of the object. We know that this is true because a very massive object requires a much greater force to lift it than a less massive object.

  • Related Demos

    The following demonstrations illustrate this physics topic:

    Sponsored by the Physics Department and the Center for Science, Mathematics, and Engineering Education -- University of Virginia