Two banked curves have the same radius. curve a is banked at 12.7 °, and curve b is banked at an angle of 15.1°. a car can travel around curve a without relying on friction at a speed of 19.1 m/s. at what speed can this car travel around curve b without relying on friction?

20.88 m/s

Explanation:

Curve A:

theta = 12.7, vA = 19.1 m/s

Curve B:

Theta = 15.1 degree

Let the speed is v.

By the use of given formula

tanθ = v^2 / rg

For Curve A

tan 12.7 = (19.1)^2 / r g   (1)

For Curve B

tan 15.1 = v^2 / r g       (2)

Divide equation (2) by equation (1), we get

tan 15.1 / tan 12.7  = v^2 / (19.1)^2

0.269 / 0.225 = v^2 / 364.81

v = 20.88 m/s

whichever one it is, it's definitely not one that you included on the list you provided.

air exerts forces on falling objects near earth’s surface.

explanation:

the term 'free falls' refer to object that are falling towards the earth, in a situation in which gravity is the only force acting on the object.

for an object in free fall, the acceleration is constant (g, the gravitational acceleration), and so the velocity of the object constantly increases.

for objects near earth's surface, there is always another force acting on the object: the resistance due to the air. this force is opposed to the direction of fall of the object, and it is proportional to the velocity of the object, so as the object falls down, this force increases up to a point when it balances the force of gravity, and the object continues its motion at constant velocity (called terminal velocity). since in this case gravity is not the only force acting on the object, we are not in a situation of free fall.