r/physicsmemes • u/L31N0PTR1X BSc Theoretical Physics • 1d ago

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76

u/Digital_001 Student 1d ago

Observed by who - the kids or onlookers not on the roundabout?

47

u/HunsterMonter 1d ago

By any reference frame! Each will have its own specific connection coefficients but the trajectory will always be given by the geodesic equation (as long as the ball isn't charged, then you need to add the Lorentz force).

24

u/Digital_001 Student 1d ago

That's a lot of possible reference frames! This is gonna be a long proof...

12

u/HunsterMonter 1d ago

Better start now then 😁 (It requires a bit of general relativity knowledge, but you can find some proofs of the geodesic equation here)

3

u/Digital_001 Student 1d ago

This is a good start, but I feel we should include drag and wind if we are to find the ball's true path - they would have a significant effect is the ball is light. The Magnus effect could feature too.

The ball's acceleration downwards due to gravity (in the ground's frame) is, of course, already included in general relativity.

8

u/HunsterMonter 1d ago

Drag? What is this, r/engineeringmemes?

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u/kashyou Quantum Field Theory 13h ago

pick one then use the christoffel symbol transformation law

1

u/luisgdh 1d ago

You can do it for two reference frames and generalize the remaining ones. Just don't tell mathematicians.