# Find angular momentum of a body moving around other in elliptical path?

• vkash
In summary, the conversation discusses the angular momentum of a planet orbiting around the sun in an elliptical path. The maximum and minimum distances of the planet from the sun are r1 and r2. To find the angular momentum, the velocity at either perihelion or aphelion is needed, and kinetic and potential energy play a role. The conversation also mentions the importance of knowing the orbital parameters extrapolated from the perihelion and aphelion distances.
vkash
planet of mass m is moving in an elliptical orbit around the sun of mass M. maximum and minimum distance of the planet from the sun is r1 and r2. Find the angular momentum of planet about the sun.(Consider M to be fixed in it's position.)

Angular momentum= m(R*v)
At farthest point from sun angular momentum is mr2v2
and at the closest point it is mr1v1
I am thinking to make third equation with the forces of interaction between the two bodies bodies. that might be something like centrifugal force = gravitational force of interaction, but i don't know that value of instantaneous radius of curvature of the m at the two points.

So this is my problem. what should i do?

What information about the orbital parameters can you extrapolate from the perihelion and aphelion distances?

To find the angular momentum it seems that it'd be handy to know the velocity at either perihelion or aphelion. Sounds like kinetic and potential energy will play a role...

gneill said:
What information about the orbital parameters can you extrapolate from the perihelion and aphelion distances?

To find the angular momentum it seems that it'd be handy to know the velocity at either perihelion or aphelion. Sounds like kinetic and potential energy will play a role...
thanks! . these words are enough to hint me. (why didn't it strike in my mind)

r1 is the closest point on the major axis of elliptical path of planet(idk is it perihelion or aphelion). and the farthest distance that also lies on major axis is r2

## 1. What is angular momentum?

Angular momentum is a property of a moving object that describes its tendency to continue rotating around an axis. It is calculated by multiplying the object's moment of inertia by its angular velocity.

## 2. How is angular momentum related to circular motion?

In circular motion, an object's angular momentum remains constant as long as there is no external torque acting on it. This principle is known as the conservation of angular momentum.

## 3. How do you find the angular momentum of a body moving in an elliptical path?

To find the angular momentum of a body moving in an elliptical path, you need to know the object's moment of inertia and its angular velocity. The moment of inertia can be calculated using the object's mass, radius, and the distance between the center of mass and the axis of rotation.

## 4. Can the angular momentum of an object change?

Yes, the angular momentum of an object can change if there is an external torque acting on it. This can be seen in situations such as a spinning top slowing down due to friction or a figure skater changing their angular momentum by extending their arms.

## 5. How is the angular momentum of a body moving in an elliptical path affected by changes in its orbit?

The angular momentum of an object moving in an elliptical path remains constant unless there is an external torque acting on it. Therefore, changes in the object's orbit, such as an increase or decrease in its speed, will not affect its angular momentum as long as there are no external forces involved.

• Introductory Physics Homework Help
Replies
10
Views
439
• Introductory Physics Homework Help
Replies
335
Views
10K
• Introductory Physics Homework Help
Replies
1
Views
980
• Introductory Physics Homework Help
Replies
26
Views
374
• Introductory Physics Homework Help
Replies
10
Views
1K
• Introductory Physics Homework Help
Replies
9
Views
1K
• Introductory Physics Homework Help
Replies
2
Views
1K
• Introductory Physics Homework Help
Replies
9
Views
2K
• Introductory Physics Homework Help
Replies
15
Views
2K
• Introductory Physics Homework Help
Replies
13
Views
1K