Circular and Rotational Motion

An object moves in a circular path at a constant speed. Compare the direction of the object's velocity and acceleration vectors.

• Both vectors point in the same direction

• the vectors point in opposite directions

• the vectors are perpendicular

• the question is meaningless, since the acceleration is zero.

When an object experiences uniform circular motion, the direction of the acceleration is:

• in the same direction as the velocity vector

• in the opposite direction of the velocity vector

• is directed toward the center of the circular path

• is directed away from the center of its circular path

When an object experiences uniform circular motion, the direction of the net force is

• is in the same direction as the motion of the object

• in the opposite direction of the motion of the object

• is directed toward the center of the circular path

• is directed away from the center of the circular path

A pilot executes a vertical dive then follows a semi-circular arc until it is going straight up. Just as the plane is at its lowest point, the force on him is

• less than mg, and pointing up

• less than mg, and pointing down

• more than mg, and pointing up

• more than mg, and pointing down

A car goes around a curve of radius r at constant speed v. Then it goes around a curve of radius 2r at speed 2v. What is the centripetal force on the car as it goes around the second curve, compared to the first?

• four times as big

• twice as big

• one-half as big

• one-fourth as big

An object moves with constant speed of 30 m/s on a circular track of radius 150 m. What is the acceleration of the object?

• zero

• 0.17 m/s²

• 5.0 m/s²

• 6.0 m/s²

A point on a wheel rotating at 5.00 rev/s is located 0.200 m from the axis. What is the centripetal acceleration?

• 0.050 m/s²

• 1.35 m/s²

• 48.0 m/s²

• 198 m/s²

How many revolutions per minute must a circular, rotating space station of radius 1000 m rotate to produce an artificial gravity of 9.80 m/s²?

• 0.65 rpm

• 0.75 rpm

• 0.85 rpm

• 0.95 rpm

A car is negotiating a flat curve of radius 50 m with a speed of 20 m/s. The force provided by friction is 1.2x10⁴ N. What is the mass of the car?

• 500 kg

• 1000 kg

• 1500 kg

• 2000 kg

A car goes around a flat curve of radius 50 m at a speed of 14 m/s. What must be the minimum coefficient of friction between the tires and the road for the car to make the turn?

• 0.20

• 0.40

• 0.60

• 0.80