Throwing an object in a moving car

[musubi racing]

is there an equation to describe object thrown from backseat to dashboard, in a sedan going 80 down the freeway
as compared to object thrown same distance outside of stationary vehicle?

 

[Nugatory]

Try googling for "Galilean relativity", that will get you started.

The concept is pretty simple: if both objects are thrown with speed $V$ and cover a distance $D$ (so spend time $T=D/V$ in flight) according to the person doing the throwing, and for simplicity both throws happen at the same time, street guy will say that the car object was thrown with speed $80+V$; car guy will say that the street object was thrown with speed $80-V$. Both will agree that the object spent the same amount of time in flight, and distance=speed*time will get the distance traveled and the position of both objects at any moment according to either of them.