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

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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.
 
I asked a question here, probably over 15 years ago on entanglement and I appreciated the thoughtful answers I received back then. The intervening years haven't made me any more knowledgeable in physics, so forgive my naïveté ! If a have a piece of paper in an area of high gravity, lets say near a black hole, and I draw a triangle on this paper and 'measure' the angles of the triangle, will they add to 180 degrees? How about if I'm looking at this paper outside of the (reasonable)...
From $$0 = \delta(g^{\alpha\mu}g_{\mu\nu}) = g^{\alpha\mu} \delta g_{\mu\nu} + g_{\mu\nu} \delta g^{\alpha\mu}$$ we have $$g^{\alpha\mu} \delta g_{\mu\nu} = -g_{\mu\nu} \delta g^{\alpha\mu} \,\, . $$ Multiply both sides by ##g_{\alpha\beta}## to get $$\delta g_{\beta\nu} = -g_{\alpha\beta} g_{\mu\nu} \delta g^{\alpha\mu} \qquad(*)$$ (This is Dirac's eq. (26.9) in "GTR".) On the other hand, the variation ##\delta g^{\alpha\mu} = \bar{g}^{\alpha\mu} - g^{\alpha\mu}## should be a tensor...

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