Hi,
Just saw your post and though I guess the answer may come a bit late here it is anyway:
You need to work separately the two relevant coordinates (vertical and horizontal).
Calculate the time the keys will take to fall the 80m of the cliff (vertical acceleration of g (due to gravity) with...
I am not sure but I guess you mean why use the static coeficient instead of the dynamic.
Note that the wheels are spining and in fact their surface is statically adhered to the road surface. Only if the car looses grip (for example going too fast in the turn) and starts to slide the...