(Multiple choice)

(1)

A car speeds along the curved exit ramp of a freeway. The radius of the curve is 80 m. A 70-kg passenger holds the arm rest of the car door with a 220-N force to keep from sliding across the front seat of the car. (Assume that the exit ramp is not banked and ignore friction with the car seat.) What is the car's speed? 

(a) 16 m/s 

(b) 57 m/s 

(c) 18m/s 

(d) 50 m/s 

(e) 28 m/s

(2)

True/false

The terminal speed of an object depends on its shape.

(3)

As a sky diver falls through the air, her terminal speed

(a) Depends on her mass. 

(b) Depends on her orientation as she falls. 

(c) Depends on the density of the air. 

(d) Depends on all of the above.

(4)

The mass of the moon is about 1% that of the earth. The centripetal force that keeps the moon in its orbit around the earth 

(a) Is much smaller than the gravitational force exerted on the moon by the earth. 

(b) Depends on the phase of the moon. 

(c) Is much greater than the gravitational force exerted on the moon by the earth. 

(d) Is the same as the gravitational force exerted on the moon by the earth. 

(e) I cannot answer; we haven't studied Newton's law of gravity yet.

(5) True or false:

Centripetal force is one of the four fundamental forces.

(6)

On an icy winter day , the coefficient of friction between the tires of a car and a roadway might be reduced to one-half of its value on a dry day. As a result, the maximum speed at which a curve of radius R can be safely negotiated is 

(a) The same as on a dry day. 

(b) Reduced to 71% of its value on a dry day. 

(c) Reduced to 50% of its value on a dry day. 

(d) Reduced to 37% of its value on a dry day. 

(e) Reduced by an unknown amount depending on the car's mass.

(7)

An object with a mass of 5.5 kg is allowed to slide from rest down an inclined plane. The plane makes an angle of 30° with the horizontal and is 72 m long. The coefficient of kinetic friction between the plane and the object is 0.35. The speed of the object at the bottom of the plane is 

(a) 5.3 m/s. 

(b) 15 m/s. 

(c) 24 m/s. 

(d) 17 m/s. 

(e) 11 m/s.