saw the article in today’s paper about the hovering humming bird in a braking car.
well, here’s another ? for u.
what happens to a tethered helium filled balloon when u brake?
since acceleration forces and gravity forces are equivalent, the gravity vector (the down direction) rotates towards the front of the car. The balloon reacts to this force and moves toward the back of the car. Try it and see but keep one eye on the road 
actually, i suspect the humming bird would quickly react to the changing gravity direction and reorient itself! i’ve seen them station keep in some pretty violent winds.