“Chasing Vertices: A Time-Bound Pursuit Problem in a Square”

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SUMMARY

The discussion focuses on a time-bound pursuit problem involving two mice moving in a spiral towards the center of a square. The velocities of the mice are perpendicular and maintain a constant radial component, which simplifies the calculation of their displacement. The key conclusion is that while the velocities change direction, the radial component remains constant, allowing for the determination of distance reduction over a time interval, denoted as ##dt##.

PREREQUISITES
  • Understanding of basic kinematics and velocity components
  • Familiarity with the concept of radial motion
  • Knowledge of geometric properties of squares
  • Ability to perform calculus operations related to time intervals
NEXT STEPS
  • Explore the mathematical formulation of radial velocity in pursuit problems
  • Learn about the implications of constant velocity components in dynamic systems
  • Study the geometric transformations of shapes under motion
  • Investigate average velocity calculations in non-linear paths
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This discussion is beneficial for mathematicians, physicists, and students studying dynamics and kinematics, particularly those interested in pursuit curves and motion in constrained geometries.

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Homework Statement
Consider a square with a side length of 1 meter. At each vertex of the square, there is a point. Each point moves at a constant speed of 1 meter per second, and the direction of movement is always towards the next vertex. In other words, point 1 moves towards point 2, point 2 moves towards point 3, point 3 moves towards point 4, and point 4 moves towards point 1. How long will it take for all the points to meet at the center?
Relevant Equations
Whatever equations work. Was given to us while learning about vectors.
I know that the velocities are perpendicular to each other and that they are moving in a spiral and that they will meet in the centre of the square. From that, I know the displacement of the point but I do not know how to get the time, since the velocity is always changing direction. Could I somehow take the average velocity?
 
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The radial component (towards the center) of each velocity has the same magnitude during the spiraling towards the center.
 
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nasu said:
The radial component (towards the center) of each velocity has the same magnitude during the spiraling towrads the center.
The implication is that the square remains a square as it shrinks. (As was already clear).

The radial component is independent of scale. So it is constant over time.
 
jansons said:
since the velocity is always changing direction
Two mice are one meter apart. By how much is that distance reduced in a time interval of ##dt## ? :wink:

[edit]
This one is known as the mice problem. See also Radiodrome

##\ ##
 
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The book claims the answer is that all the magnitudes are the same because "the gravitational force on the penguin is the same". I'm having trouble understanding this. I thought the buoyant force was equal to the weight of the fluid displaced. Weight depends on mass which depends on density. Therefore, due to the differing densities the buoyant force will be different in each case? Is this incorrect?

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