Why does the law of gravitation only apply to particles and spheres???

The law of gravitation applies to all objects.

The gravitational formula considers the interaction between two prime points. When the rotation of the homogeneous sphere is not considered, the homogeneous sphere can be considered as a particle, so the law of gravitation applies. When finding the gravitational force for ordinary objects, the general method is to find the gravitational force of each particle, and then superimpose the gravitational vectors of all the particles, so as to obtain the final gravitational resultant.

The result thus obtained is inconsistent with the result obtained using the formula of gravitation, which treats the object as a particle, (except for a homogeneous sphere). Therefore, the gravitational formula only applies to particles and spheres.

If two objects cannot be regarded as particles, the size and shape cannot be ignored, although there is a gravitational force between them, in the formula for calculating gravitational force, the distance between them is related to the shape and size, and it is difficult to determine. For spheres with uniform mass distribution, they can generally be regarded as particles. Therefore, the calculation of gravitation is generally applicable to the calculation of gravity between particles.

The gravitational force between objects that cannot be regarded as particles requires integral knowledge to solve.

In layman's terms, the gravitational formula is relatively simple to calculate particles and spheres. So everybody calculates this way, which gives you the illusion that it only applies to particles and spheres.

The law of gravitation applies to all objects that have mass. It's just that the gravitational force of particles and spheres is the simplest, and homework exams are much more common.

Summary. Dear dear, in the case where the object mass is on the surface of the earth, the law of gravitation still applies, but it can be ignored because the mass of the object is very small as compared to the mass of the earth, the gravitational pull exerted by the earth is relatively strong, and the gravitational force exerted by the object on the earth is relatively small and can be considered negligible.

If the object is on the surface of the earth, can the law of gravitation be ignored?

Hello dear, in the case where the object mass is on the surface of the earth, the law of gravitation still applies, but it can be ignored because the mass of the object is very small compared to the mass of the earth and the gravitational force exerted by the earth on the object is relatively strong, while the gravitational force exerted by the object on the earth of Suichun is relatively small and can be considered negligible.

Hello dear, in many practical situations, we can think of the earth as a constant gravitational field, and use Newton's laws of gravitational force to calculate the disturbance of the chain of thought of an object on the surface of the earth, without considering the gravitational force of the object itself. However, in physics problems with extreme precision or high precision, the law of gravitation still needs to be considered.

1. Broadly speaking, the law of gravitation is applicable to the calculation of gravitational force between all objects. The applicable conditions of the formula of the law of gravitation in high school physics: only for particles or objects that can be considered as particles.

2. Gravitational force does not mean that all matter only has gravitational force, for example: two gases do not necessarily attract each other, and high-energy particles do not necessarily attract each other. Gravitation simply says that there is a gravitational force between objects.

Of course, not all objects have a gravitational attraction between them, for example, homogeneous magnets are repulsive.

First of all, how to find the gravitational force of an object on the adjacent particle a.

Let the distance between a tiny mass element dm and the particle a on any object be rThen the gravitational attraction of the mass element to the point a is: ;

The gravitational force of the whole object on it: the integral of the above equation to the only ho dm.

In general, DM has a definite relationship with volumetric elements, and DV is a function of r and angle a. This translates into the integration of a function to dr. Just find the points.

In the same way, it is possible to find the net force of any particle on one object receiving another object. In this case, the proposition "What is the gravitational pull of one object on another object" is meaningless. ,4,Help with the points???

I really can't integrate, I will integrate a vt+1 2at*2, how to find gravitational force when two objects can't be regarded as particles.

I just learned the gravitational force formula, but the teacher said that this formula can only be used for the operation between two particles, when r is too small, because the two objects can no longer be regarded as particles, so this formula is not used, so how to find the gravitational force between non-particles, see others say to use calculus, please ask what the specific method is.

The radius of a uniform sphere is r, the distance of a particle in the sphere from the center of the sphere is r, and the gravitational force gmm r

where m is the mass within the radius r and m is the mass of the particle).

The law of gravitation, fibrillation, applies only to particles.

All objects in the universe are attracted to each other, and the gravitational force is proportional to the product of the mass of the object, inversely proportional to the square of the distance, and the direction is on the line connecting the vertical and the two.

Calculation formula. f=gm1m2/r^2

Applicable conditions: Interaction between particles.

In reality, there is no such thing as a particle, as long as the distance between two objects is much greater than its size, the object can be regarded as a particle.

Applications: celestial movements, artificial earth satellites.

In fact, it is also larger, but the distance cannot be small to a certain extent, because Newton's mechanics is particle mechanics. To a certain extent, it becomes the gravitational force between atoms, or even between gluons, and the gravitational force is not dominant at this time, because the mass of the particle is too small, and the electromagnetic phase force and strong force are much greater than it, anyway, Newtonian mechanics cannot be used. So don't imagine that the distance between two macroscopic objects can be very small.

For your addition, as long as the distance is much larger than the radius of the celestial body, it can be regarded as a particle, for example, the gravitational attraction of the sun on the earth, but the gravitational force exerted by the earth on the sun cannot be regarded as a particle.

Strictly speaking, the formula of the law of gravitation is only applicable to finding the gravitational force between two particles, and when using this formula to find the gravitational force between spheres with uniform mass distribution, r in the formula is the distance between the centers of the two spheres

So the answer is: particles, two spheres

f(r^2-r^2)/(2r)

f(r)=gmm/r^2

m=4 3*pi*density*r3

f(r)=gm*(4 3*pi*density*r3) r2=gm*4 3*pi*dense group report*r=(gm*4 3*pi*density)*r=k*r

and f(r)=kr=f

e(r)=f(r)·r 2=kr 2 2=f·r 2 (2r)e=e(r)-e(r)=f·r Lead pure2-f·r 2 (2r)=f(r 2-r 2) (2r).