# Gravitation (planetary motion)

• Samsmith47
In summary, the particle is moving in circular orbit such a way that the net force (F) is always towards the point p (point p is on the circumference of circle). The variation of force F with respect to r is -5.
Samsmith47
Homework Statement
The particle is moving in circular orbit such a way that the net force (F) is always towards the point p (point p is on the circumference of circle). Find the variation of force F with respect to r.
i.e find the value of n in the expression F=kr^n
Relevant Equations
F=kr^n
Da/dt= l/2m
Homework Statement: The particle is moving in circular orbit such a way that the net force (F) is always towards the point p (point p is on the circumference of circle). Find the variation of force F with respect to r.
i.e find the value of n in the expression F=kr^n
Homework Equations: F=kr^n
Da/dt= l/2m

But I am getting -3

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Samsmith47 said:
Homework Statement: The particle is moving in circular orbit such a way that the net force (F) is always towards the point p (point p is on the circumference of circle). Find the variation of force F with respect to r.
i.e find the value of n in the expression F=kr^n
Homework Equations: F=kr^n
Da/dt= l/2m

Homework Statement: The particle is moving in circular orbit such a way that the net force (F) is always towards the point p (point p is on the circumference of circle). Find the variation of force F with respect to r.
i.e find the value of n in the expression F=kr^n
Homework Equations: F=kr^n
Da/dt= l/2m

But I am getting -3
Your diagram is too messy to decipher, so I do not know what your variables represent.
Please post a clearer diagram and (as text, not an image) definitions of your variables and consequent working.

Is it possible that your sketch is a misinterpretation of the problem description? If p is on the orbit, when the particle comes around to the location of p, the force would become infinite (with n being a negative exponent). I am assuming that r is the distance to p. And in that case, I can not see why the particle has a circular orbit. Could it be that p is on the circumference of some other circle? Clarify.

sojsail said:
when the particle comes around to the location of p, the force would become infinite
Not sure that that is a problem in this artificial scenario.

Samsmith47 said:
But I am getting -3
I can see how you would get that if you were to confuse the angular rate of orbit about the centre of the circle with that about P.

Thanks for seeing my response I will draw the dia neatly and send again
And also I got the answer thanks for trying I am really greatfull

## 1. What is gravitation?

Gravitation is a natural phenomenon by which all objects with mass are brought toward one another. It is the force that governs the motion of planets, stars, galaxies, and other celestial bodies in the universe.

## 2. What is the law of gravitation?

The law of gravitation was first described by Sir Isaac Newton in his famous work "Principia" in 1687. It states that every object in the universe attracts every other object with a force that is directly proportional to their masses and inversely proportional to the square of the distance between them.

## 3. How does gravitation affect planetary motion?

Gravitation is responsible for the elliptical orbits of planets around the sun. The gravitational pull of the sun keeps the planets in their respective orbits and prevents them from flying off into space. It also affects the speed at which planets move, with planets closer to the sun moving at a faster speed due to the stronger gravitational force.

## 4. What is the difference between gravitation and gravity?

Gravitation is the natural phenomenon that describes the attraction between objects with mass, while gravity is the actual force of attraction between objects. In other words, gravitation is the concept, while gravity is the physical force.

## 5. Can gravitation be explained by Einstein's theory of relativity?

Yes, gravitation can be explained by Einstein's theory of relativity, specifically the theory of general relativity. This theory states that the force of gravity is not a force at all, but rather a result of the curvature of space and time caused by massive objects. It provides a more accurate description of gravitation in extreme situations, such as near black holes or during the expansion of the universe.

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