What Happens When a Ball Is Thrown in a Moving Car?

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Discussion Overview

The discussion revolves around the behavior of a ball thrown in a moving car, particularly focusing on the implications of relativity and external forces such as air resistance. Participants explore theoretical frameworks and practical considerations related to this scenario.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants assert that according to the theory of relativity, an object inside a uniformly moving car behaves as if it is at rest, leading to questions about where the ball would land when thrown.
  • Others challenge this by questioning whether the open roof of the car would affect the outcome compared to a closed roof, suggesting that external factors like air resistance must be considered.
  • One participant introduces the concept of air resistance and drag, noting that in a real-world scenario, these forces would influence the ball's trajectory, contrasting it with an idealized vacuum situation.
  • Another participant mentions that the scenario is better explained by Galilean relativity, emphasizing that the wind created by the car's motion would impact the ball thrown through an open roof.
  • A reference is made to a resource discussing classical physics that may provide further insights into the topic.

Areas of Agreement / Disagreement

Participants do not reach a consensus, as there are competing views regarding the effects of air resistance and the relevance of different frames of reference in this scenario.

Contextual Notes

Participants express uncertainty about the influence of external forces like air resistance and the assumptions underlying their thought experiments, particularly regarding the ideal conditions versus real-world scenarios.

sunney
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acoording to theory of relativity, if a car is moving at a uniform speed then any object inside that car behave like its in rest. so what happens if a man throws a ball in an open roof car which is at uniform speed, where that ball is likely to land , assuming no other external force is applied to the ball ?
 
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sunney said:
acoording to theory of relativity, if a car is moving at a uniform speed then any object inside that car behave like its in rest. so what happens if a man throws a ball in an open roof car which is at uniform speed, where that ball is likely to land , assuming no other external force is applied to the ball ?
Have you tried the experiment in a closed roof car? Do you expect that an open roof will make a difference?
 
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What happens when you spit your gum out on the freeway? Why do you think it would be different out of an open roof? (Hint: Air Resistance/Drag)

Most thought experiments like this are made with the assumption of being in a vacuum, where no wind resistance is at play. If this were in a vacuum and the ball was to be thrown straight up, it would come right back down to where it was released provided no that other forces were present besides gravity. However, in the real world, that ball

https://en.wikipedia.org/wiki/Drag_(physics)
https://en.wikipedia.org/wiki/Vacuum

I hope that helps!
 
This is a question fully addressed by Galilean relativity, as the relative speeds are so low. In an open roof, in the frame of the car, there is a wind blowing around the car which will obviously affect a ball thrown through an open roof. Note that the principle of relativity was known in Galileo's time, as was an understanding that this example in no way 'questions' the principle.
 
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If you have Audible, Great Ideas of Classical Physics with Steven Pollock addresses this in the second chapter too.
 

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