Solving Complex Trajectory Puzzle: Find m's Path Equation

  • Context: Graduate 
  • Thread starter Thread starter brupenney
  • Start date Start date
  • Tags Tags
    Complex Trajectory
Click For Summary

Discussion Overview

The discussion revolves around a physics puzzle involving the trajectory of a mass m moving in space towards a circular mass M. The mass m has a constant velocity C and experiences an additional velocity Ve directed towards M, which depends on its distance from M. Participants seek to derive the equation of m's path as it moves from infinity to a position directly over the center of M.

Discussion Character

  • Exploratory
  • Technical explanation
  • Mathematical reasoning

Main Points Raised

  • One participant poses the initial problem, asking for the path equation of mass m given its velocities and initial conditions.
  • Another participant suggests deriving differential equations, noting that the problem appears more manageable in polar coordinates than Cartesian coordinates.
  • Clarification is sought regarding the distance of the undeviated path from the center of M and the meaning of "overright."
  • A participant defines "overright" as the position where the angle from the undeviated path to the center of M results in the smallest separation.
  • Discussion includes determining the velocity at a point (r, θ) in polar coordinates and how this relates to the radial and tangential components of motion.
  • One participant expresses uncertainty about how to approach the problem despite having some calculus knowledge, indicating a potential gap in understanding the necessary concepts.
  • Further inquiry is made into the relationship between the velocities in the radial and tangential directions and their connection to the derivatives \(\dot{r}\) and \(\dot{\theta}\).

Areas of Agreement / Disagreement

Participants do not reach a consensus on the solution to the problem, and multiple viewpoints and uncertainties about the approach and definitions remain evident throughout the discussion.

Contextual Notes

Participants express confusion regarding specific terms and the mathematical approach needed to solve the problem, indicating potential limitations in their understanding of the underlying physics and mathematics.

brupenney
Messages
15
Reaction score
0
Can anyone solve this puzzle for me - a mass m in space with a constant velocity C heads toward a circular mass M such that if not disturbed it would pass by M at a distance of 2 of M's radiuses. However, the mass m experiences a second velocity Ve towards the center of M; the magnitude of this V is given by k(d^-1/2) where d is the radial distance to M's center. m starts its journey at infinity and ends up overright the center of M. What is the equation of m's path?

I'm not sure whether or not this is clear. A diagram would be needed ideally.
 
Physics news on Phys.org
Can you derive a differential equation or two? (I did. Looked a bit better in polar than in Cartesian, but still rather nasty.) Btw, is the undeviated miss by two radii from the centre or from the surface? And what is "overright"?
 
From the center. I cannot get anywhere with this problem
 
By overright I mean at an angle from the deviated path or undeviated path to the center of M is such that their separation is the smallest it can be.
 
Taking the centre of M as the origin in polar co-ordinates, and θ=0 being the undeviated direction:
- what is the velocity when at (r, θ)
- what does that give you for [itex]\dot{r}[/itex] and [itex]\dot{\theta}[/itex]
 
If I understand your question, the velocity at (r,theta) is the vector sum of C and Ve at an angle theta.

I know some calculus, integral and differential, but I just can't figure how to approach this problem, and I may not have enough knowledge to solve it even then.
 
brupenney said:
If I understand your question, the velocity at (r,theta) is the vector sum of C and Ve at an angle theta.
OK, so what is the velocity in the radial direction? In the tangential direction? How do these relate to r-dot and theta-dot?
 

Similar threads

  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 1 ·
Replies
1
Views
2K
Replies
4
Views
2K
  • · Replies 1 ·
Replies
1
Views
3K
  • · Replies 9 ·
Replies
9
Views
3K
  • · Replies 11 ·
Replies
11
Views
2K
Replies
9
Views
2K
  • · Replies 14 ·
Replies
14
Views
3K
  • · Replies 9 ·
Replies
9
Views
3K
  • · Replies 6 ·
Replies
6
Views
3K