Difference between revisions of "gravity"
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'''gravity''' is the tendency of objects with mass to accelerate toward each other. | '''gravity''' is the tendency of objects with mass to accelerate toward each other. | ||
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| + | '''Newton's law of universal gravitation''' states the following: | ||
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| + | Every point mass attracts every other point mass by a force directed along the line connecting the two. This force is proportional to the product of the masses and inversely proportional to the square of the distance between them: | ||
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| + | F = G \frac{m_1 m_2}{r^2} | ||
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| + | where: | ||
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| + | F is the magnitude of the (repulsive) gravitational force between the two point masses | ||
| + | G is the gravitational constant | ||
| + | m1 is the mass of the first point mass | ||
| + | m2 is the mass of the second point mass | ||
| + | r is the distance between the two point masses | ||
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| + | Assuming SI units, F is measured in newtons (N), m1 and m2 in kilograms (kg), r in metres (m), and the constant G is approximately equal to 6.67 × 10−11 N m2 kg−2 (newtons times metres squared per kilogram squared). | ||
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| + | It can be seen that the repulsive force F is always negative, which means that the net attractive force is positive. (This sign convention is adopted in order to be consistent with Coulomb's Law, where a positive force means repulsion between two charges.) | ||
[[Category:Glossary]] | [[Category:Glossary]] | ||
{{Stub}} | {{Stub}} | ||
Revision as of 11:03, 13 April 2006
gravity is the tendency of objects with mass to accelerate toward each other.
Newton's law of universal gravitation states the following:
Every point mass attracts every other point mass by a force directed along the line connecting the two. This force is proportional to the product of the masses and inversely proportional to the square of the distance between them:
F = G \frac{m_1 m_2}{r^2}
where:
F is the magnitude of the (repulsive) gravitational force between the two point masses G is the gravitational constant m1 is the mass of the first point mass m2 is the mass of the second point mass r is the distance between the two point masses
Assuming SI units, F is measured in newtons (N), m1 and m2 in kilograms (kg), r in metres (m), and the constant G is approximately equal to 6.67 × 10−11 N m2 kg−2 (newtons times metres squared per kilogram squared).
It can be seen that the repulsive force F is always negative, which means that the net attractive force is positive. (This sign convention is adopted in order to be consistent with Coulomb's Law, where a positive force means repulsion between two charges.)