What is the answer to this physics riddle?

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SUMMARY

The forum discussion centers on the physics riddle involving the Brachistochrone problem, which examines the fastest path between two points under the influence of gravity. Participants analyze various paths, including straight lines and curves, and discuss how factors like initial velocity and path shape affect travel time. Key equations are presented, including time calculations for different trajectories, emphasizing that the Brachistochrone curve is always the fastest path. Ultimately, the conclusion is that while some paths below the horizontal can be faster, not all are guaranteed to outperform a flat trajectory.

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  • Understanding of the Brachistochrone problem in physics
  • Familiarity with basic kinematics and gravitational motion
  • Knowledge of calculus, particularly integration techniques
  • Ability to analyze motion along curved paths and their implications
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  • Study the mathematical derivation of the Brachistochrone curve
  • Explore the principles of energy conservation in gravitational systems
  • Learn about the role of initial velocity in trajectory optimization
  • Investigate the effects of friction on motion along different paths
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Physics students, educators, and enthusiasts interested in classical mechanics and optimization problems involving motion under gravity.

  • #31
Borek said:
Then how come brachistochrone exists, if time on all curves is identical?
But it isn't one. The more on kinetic energy gained downwards is lost again upwards. (But I haven't done the math, maybe it doesn't cancel out, however I think it does. I desperately try to remember the analogous experiment in a math museum I once visited, I thought they were equally fast at the finish ...)
 
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  • #32
fresh_42 said:
But it isn't one. The more on kinetic energy gained downwards is lost again upwards. (But I haven't done the math, maybe it doesn't cancel out, however I think it does.)

The final speed must be the same (without friction) but the ball will take different times for different paths. For example, you can have a path with a time to the lowest point as large as you wish!
 

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