In fig. 6-57, a stuntman drives a car (without negative lift) over the top of a hill, the cross section of which can be approximated by a .whatis the greatest speed at which he can drive without the car leaving the road at the top of the hill?

49.5m/s

Explanation:

The vertical force must be equal to the centripetal force. In the limit case when the contact force is just 0N (just almost leaving the ground, slower there is more contact and faster will leave the ground) the only vertical force acting on the car will be its weight, so this must be equal to the centripetal force , and then we use the definition of weight and the equation for centripetal force:

And solve for the velocity:

Using our values:

answer;

d. are made mostly of liquid

explanation;

-the general   composition and structure planets includes; they have a thick gas and liquid layer covering a small,solid core. mostly the gases are hydrogen and helium atmosphere and layers of liquid hydrogen. for instance neptune and uranus are examples of the outer planets, they have a core covered by ice and ammonia.

-neptune's atmosphere is hydrogen and helium with a bit of methane so there is no oxygen to breath and the interior is made up of frozen water and ammonia with a rock and iron core. thus, there is no liquid water or solid surface to survive.