# B Theory of relativity

1. Aug 9, 2016

### sunney

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 ?

2. Aug 9, 2016

### jbriggs444

Have you tried the experiment in a closed roof car? Do you expect that an open roof will make a difference?

3. Aug 15, 2016

### mitchel

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!

4. Aug 15, 2016

### PAllen

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.

5. Aug 15, 2016

### mitchel

If you have Audible, Great Ideas of Classical Physics with Steven Pollock addresses this in the second chapter too.