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The equation for universal gravitation thus takes the form: =, where F is the gravitational force acting between two objects, m 1 and m 2 are the masses of the objects, r is the distance between the centers of their masses, and G is the gravitational constant.
The first equation shows that, after one second, an object will have fallen a distance of 1/2 × 9.8 × 1 2 = 4.9 m. After two seconds it will have fallen 1/2 × 9.8 × 2 2 = 19.6 m; and so on. On the other hand, the penultimate equation becomes grossly inaccurate at great distances.
This is because the gravitational force is an extremely weak force as compared to other fundamental forces at the laboratory scale. [d] In SI units, the CODATA-recommended value of the gravitational constant is: [1] = 6.674 30 (15) × 10 −11 m 3 ⋅kg −1 ⋅s −2. The relative standard uncertainty is 2.2 × 10 −5.
Moreover, words which are synonymous in everyday speech are not so in physics: force is not the same as power or pressure, for example, and mass has a different meaning than weight. [11] [12]: 150 The physics concept of force makes quantitative the everyday idea of a push or a pull. Forces in Newtonian mechanics are often due to strings and ...
Classical mechanics is the branch of physics used to describe the motion of macroscopic objects. [1] It is the most familiar of the theories of physics. The concepts it covers, such as mass , acceleration , and force , are commonly used and known. [ 2 ]
Dividing both force equations by the respective masses, subtracting the second equation from the first, and rearranging gives the equation ¨ = ¨ ¨ = = (+) where we have again used Newton's third law F 12 = −F 21 and where r is the displacement vector from mass 2 to mass 1, as defined above. The force between the two objects, which ...
When objects are in contact, the force directly between them is called the normal force, the component of the total force in the system exerted normal to the interface between the objects. [36]: 264 The normal force is closely related to Newton's third law. The normal force, for example, is responsible for the structural integrity of tables and ...
Here, k e is a constant, q 1 and q 2 are the quantities of each charge, and the scalar r is the distance between the charges. The force is along the straight line joining the two charges. If the charges have the same sign, the electrostatic force between them makes them repel; if they have different signs, the force between them makes them attract.