A car with mass m travels over a hill with a radius of curvature of r at a speed of 15 m/s. What is the normal force on the car when the car is at the top of the hill?

zero

Explanation:

The computation of the normal force is shown below:

As we know that

F_c = mg - N

F_c = mv^2 ÷ r

N = mg - mv^2 ÷ r

N = m(g - v^2 ÷ r)

Assume that

The mass of the car is 1200 kg

And, r = 10 m

So,

= 1200 (9.8 - 15^2 ÷ 10)

= -15240 N

Since it comes in negative so the normal force would be zero