In Conceptual Physics Answers, gravity can be defined as a force that binds together progressively larger structures from star to galaxy to super cluster and may be drawing them towards the great attractor. The force not only holds you on earth, but also reaches out across intergalactic space according to Conceptual Physics Answers. Engineering in Kenya has more articles.
Physicists on Gravitation for Conceptual Physics Answers
Physicists like to study seemingly unrelated phenomena to show that a relationship can always be found if they are examined closely enough. This search for unification has been going on for centuries. For example, in 1665, Isaac Newton made a simple and yet very significant contribution to physics when he showed that the force that holds the moon in its orbit is the same force that makes an apple fall.
We take this so much for granted now that it is not easy for us to comprehend the ancient belief that the motions of earth bound bodies and heavenly bodies were different in kind and were governed by different laws according to Conceptual Physics Answers.
Newton concluded that not only does earth attract an apple and the moon but every body in the universe attracts every other body: this tendency of bodies moving towards each other is called gravitation in Conceptual Physics Answers. Newton’s conclusion takes a little getting used to because the familiar attraction of earth for earthbound bodies is so great that it overwhelms the attraction that earthbound bodies have for each other.
For example, earth attracts an apple with a force magnitude of about 0.8N. You also attract a nearby apple and it attracts you according to Conceptual Physics Answers, but the force of attraction has less magnitude than the weight of a spec of dust. Quantitatively, Newton proposed s force law that we call Newton’s law of gravitation which states that: – every particle attracts any other particle with a gravitational force whose magnitude in Conceptual Physics Answers is given by;
Hence m1 and m2 are the masses of the particles, r is the distance between them and G is the gravitational constant with a value that is given by;
G=6.67×10-11 Nm2kg-2 = 6.67×10-11m3kg-1s-2
As the figure below shows, a particle m2 attracts a particle m1 with a gravitational force F that is directed towards particle m2 and particle m1 attracts particle m2 with a gravitational force –F that is directed towards m1 according to Conceptual Physics Answers.
The force F and –F from the third law force pair; they are opposite in direction but equal in magnitude. They depend on the separation of two particles, but not their location: the particles could be a deep cave or in deep space. Also, according to Conceptual Physics Answers, F and –F are not altered by the presence of other bodies even if those bodies lie between the two particles we are considering.
The strength of the gravitational force i.e. how strongly two particles with given masses at a given separation attract each other depends on the value of the gravitational constant G. if G by some miracle were multiplied by a factor of 10, you would be crashed to the floor by earth’s attraction. If G were to be divided by this factor, earth’s attraction would be weak enough that you would jump over a building.
The Shell Theorem for Conceptual Physics Answers
Although Newton’s law of gravitation applies strictly to particles, we can also apply it to real objects as long as the sizes of the objects are small compared to the distance between them. The moon and the earth are far apart enough so that to a good approximation according to Physics in Kenya, we can treat them both as particles.
But what about gravitation between an apple and the Earth? From the point of view of the apple, the broad and level earth stretching out to the horizon beneath the apple certainly does not look like a particle. Newton solved the apple-earth problem by proving an important theorem called the shell theorem in Conceptual Physics Answers. The theorem states that: a uniform spherical shell of matter attracts a particle that is outside the shell as if all the shell’s mass were concentrated at the centre.
In Conceptual Physics Answers, earth can be thought of as a nest of such shells, one within another and each attracting a particle outside earth’s surface as if the mass of that shell were at the centre of the shell. Thus from the apple point of view, earth does behave like a particle, one that is located at the centre of the earth and has a mass equal to that of earth.
Conclusion on Conceptual Physics Answers
Gravitation is a very major topic in Conceptual Physics Answers.