Help with Circular Motion Homework: Find Gravitation Force Point

In summary, the conversation is about a homework question regarding finding the point between two masses where a third object would experience no gravitation force. The question involves calculating the net force between the two masses, using the formula \vec{F}=-\frac{Gm_1m_2}{r^2}\hat{r}. The conversation includes various attempts at solving the problem and clarifications on the concept of net force. Ultimately, the solution involves setting the gravitational attraction between the two masses equal to each other and solving for the unknown mass.
  • #1
Pepsi
14
0
I'm having troubles with one of my homework questions, and I was wondering if someone could help me with it.

okay here it is...

Q: Two masses, object A and object B are located 2m apart from each other, the mass of object a is m and the mass of object b is 4m.

Showing your calculations find the point between these two objects where a third object would experience no gravitation force.

I'm really stuck on this question, any help would be very much appreciated.
 
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  • #2
"a third object would experience no gravitation force."
what they mean is, no net gravitation force
imagine a particle C lying on the line connecting A and B - what is the force that C feels from A? what is the force that C feels from B?
What is the net force?
 
  • #3
I don't understand that at all...

I would have thought I'd try and figure out what m was = to then, maybe do that... because from what I know I don't think I can figure out the net gravititional force from just what I was given...

A little more help? heh
 
  • #4
Are you aware that the force for gravitation is
[tex]\vec{F}=-\frac{Gm_1m_2}{r^2}\hat{r}[/tex]

You have two masses m and 4m and some unknown mass m_2, so the magnitude of the gravitational attraction between m and m_2 is
[tex]F_1=\frac{Gmm_2}{r_1^2}[/tex]
where r_1 is the distance between m_2 and m. The strength of the gravitational attraction between 4m and m_2 is
[tex]F_2=\frac{G(4m)m_2}{r_2^2}[/tex]
where r_2 is the distance between 4m and m_2. If m_2 lies along the line between 4m and m and the distance between m and 4m is R, then
R=r_1+r_2, so the second equation becomes
[tex]F_2=\frac{G(4m)m_2}{(R-r_1)^2}[/tex]
If m_2 is right between A and B, then the forces act in opposite directions and so cancel each other out. When F_1-F_2=0, m_2 will feel no force.
 

1. What is circular motion?

Circular motion is the movement of an object along a circular path, where the object's distance from a fixed point remains constant but its direction continuously changes.

2. How do I calculate the gravitational force in circular motion?

To calculate the gravitational force in circular motion, you can use the formula F = (G * m * M) / r^2, where F is the gravitational force, G is the gravitational constant, m is the mass of the smaller object, M is the mass of the larger object, and r is the distance between the two objects.

3. What is the point of gravitational force in circular motion?

The point of gravitational force in circular motion is the center of the circular path, also known as the center of the circle. This is the point where the force acts on the object, causing it to continuously change direction.

4. How does the mass of an object affect circular motion?

The mass of an object affects circular motion as it determines the amount of gravitational force acting on the object. The greater the mass, the stronger the gravitational force, which can result in a higher speed or tighter circular path.

5. Can circular motion occur without gravity?

No, circular motion cannot occur without gravity. Gravity is the force that keeps an object moving in a circular path around a central point. Without gravity, the object would continue in a straight line, rather than curving around the central point.

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