Gravitational Force, the derivative of Gravitational Potential Energy?

In summary, the conversation discusses the relationship between gravitational force and potential energy, and how it relates to the unexplained pioneer anomaly. The main point is that gravitational force is the derivative of gravitational potential energy, but the validity of this statement is uncertain when the pioneer anomalous acceleration is added. The conversation also mentions that the existence of the pioneer anomaly could invalidate previous estimates of the sun's mass.
  • #1
kmarinas86
979
1
For the equation:

[itex]U=\frac{-GMm}{h}[/itex]

Where [itex]h[/itex] is the distance between the center of masses [itex]M[/itex] and [itex]m[/itex].

In Calculus, they teach you derivatives.
The derivative of [itex]U[/itex] with respect to [itex]h[/itex] is:

[itex]dU=d\left(\frac{-GMm}{h}\right)[/itex]
[itex]dU=\frac{GMm}{h^2}[/itex]

Which is the gravitational force.

Were I to apply this knowledge to the pioneer anomaly, I would deduce that the gravitational potential energy would be equal to the integral of the force with respect to [itex]h[/itex]:

[itex]g_{pioneer}=8.74*10^{-10}\frac{m}{s^2}[/itex]
[itex]dU=\frac{GMm}{h^2}+mg_{pioneer}[/itex]
[itex]dU=d\left(\frac{-GMm}{h}+mg_{pioneer}h\right)[/itex]
[itex]U=\frac{-GMm}{h}+mg_{pioneer}h[/itex]

Are my premises true?
 
Last edited:
Physics news on Phys.org
  • #2
It's not clear what you are trying to do. For one thing, the pioneer anomaly refers to an unexplained residual acceleration after all known forces (like gravity from known masses) have been accounted for.
 
  • #3
Main point:
Is the Gravitational Force the derivative of Gravitational Potential Energy?

A motive:
In case if this is correct, this would be provide information of its truth.

Secondary (following) point:
Is the main point still true if the pioneer anomalous acceleration is added into the acceleration due to gravity? Note that if the pioneer anomaly exists, it invalidates previous estimates of the sun's mass.

A motive:
In case if this is false, this would be provide information of its falsity.
 
Last edited:
  • #4
kmarinas86 said:
Main point:
Is the Gravitational Force the derivative of Gravitational Potential Energy?
Yes.

Secondary (following) point:
Is the main point still true if the pioneer anomalous acceleration is added to the acceleration due to gravity?
Again, no idea what you are doing here.
Note that if the pioneer anomaly exists, it invalidates previous estimates of the sun's mass.
Only if you assume that the unexplained acceleration is due to the gravitational attraction of the sun.

Are you trying to model the additional solar mass needed to account for the anomalous acceleration? If so, no need to work so hard. If the sun had an extra mass [itex]\Delta M[/itex], the additional acceleration would be:
[tex]\Delta g = \frac{G \Delta M}{h^2}[/tex]

where h is the distance from the sun's center to the pioneer.
 

1. What is gravitational force?

Gravitational force is a force of attraction between two objects with mass. It is one of the four fundamental forces of nature and is responsible for keeping planets in orbit around a star and objects on Earth from floating away.

2. What is the relationship between gravitational force and gravitational potential energy?

Gravitational potential energy is the energy an object possesses due to its position in a gravitational field. The derivative of gravitational potential energy is equal to the force of gravity acting on the object. This means that as an object moves closer to a massive body, its gravitational potential energy decreases and its gravitational force increases.

3. How is gravitational force calculated?

The force of gravity between two objects can be calculated using the formula F = G * (m1 * m2)/d^2, where G is the gravitational constant, m1 and m2 are the masses of the two objects, and d is the distance between them.

4. What is the direction of gravitational force?

The direction of gravitational force is always towards the center of mass of the larger object. This means that if an object is in orbit around another object, the gravitational force will always be directed towards the center of the larger object.

5. How does the derivative of gravitational potential energy affect the motion of objects?

The derivative of gravitational potential energy, which is equal to the force of gravity, determines the acceleration of an object due to gravity. This means that the stronger the gravitational force, the faster an object will accelerate towards the center of mass of the larger object.

Similar threads

Replies
3
Views
478
Replies
12
Views
2K
Replies
10
Views
934
Replies
21
Views
4K
  • Mechanics
Replies
27
Views
4K
Replies
5
Views
860
  • Introductory Physics Homework Help
Replies
19
Views
785
Replies
2
Views
881
Replies
1
Views
1K
Back
Top