At what point on the hill with the car have zero gravitational potential energy a) halfway down the hill b) at the top of the hill c)at the bottom of the hill d) it will never have zero gravitational potential energy

Gravitational potential energy of the car is given by formula

here m = mass of the car

g = gravitational field intensity

h = height of the car from reference point

so here from above formula we can say that if height of the car from reference is zero the gravitational potential energy will be zero

So here we generally took the reference point to be at bottom on the ground

so here also the gravitational potential energy will be zero at the ground

so correct answer will be

C)at the bottom of the hill

d. air pressure decreases as altitude increases.