Identify the forces that contribute to the centripetal force on the object in each of the following examples: a. a bicyclist moving around a flat, circular track, b. a bicycle moving around a flat, circular track, c. a race car turning a corner on a steeply banked curve.

A woman of mass 60 kg runs around a flat, circular track of radius 200 m at $6 \mathrm{~m} \mathrm{~s}^{-1}$. What force produces this acceleration?

A $1500 \mathrm{~kg}$ car starts from rest and drives around a flat $50-\mathrm{m}-$ diameter circular track. The forward force provided by the car's drive wheels is a constant $1000 \mathrm{~N}$. a. What are the magnitude and direction of the car's acceleration at $t=10 \mathrm{~s}$ ? Give the direction as an angle from the $r$-axis. b. If the car has rubber tires and the track is concrete, at what time does the car begin to slide out of the circle?

A cyclist pedals to exert a torque on the rear wheel of the bicycle. When the cyclist changes to a higher gear, the torque increases. Which of the following would be the most effective strategy to help you determine the change in angular momentum of the bicycle wheel? a. multiplying the ratio between the two torques by the mass of the bicycle and rider b. adding the two torques together, and multiplying by the time for which both torques are applied c. multiplying the difference in the two torques by the time for which the new torque is applied d. multiplying both torques by the mass of the bicycle and rider

A high-speed railway car goes around a flat, horizontal circle of radius 470 m at a constant speed. The magnitudes of the horizontal and vertical components of the force of the car on a 51.0 kg passenger are 210 N and 500 N, respectively. (a) What is the magnitude of the net force (of all the forces) on the passenger? (b) What is the speed of the car?

Describe all the forces acting on a child riding a horse on a merry-go-round. Which of these forces provides the centripetal acceleration of the child?

A girl on a spinning amusement park ride is 12 m from the center of the ride and has a centripetal acceleration of 17 $\mathrm{m} / \mathrm{s}^{2}$. What is the girl’s tangential speed?

Tell whether or not each of the following objects has a constant velocity and explain your reasoning. (a) A car driving around a curve at constant speed on a flat road. (b) A car driving straight up a

$$6 ^ { \circ }$$

incline at constant speed. (c) The Moon.

What are three examples of circular motion?

Explain what makes a passenger in a turning car slide toward the door of the car.

Suppose the value of G has just been discovered. Use the value of G and an approximate value for Earth’s radius ($6.38 \times 10^{6}$ m) to find an approximation for Earth’s mass.

In one amusement park ride, riders enter a large vertical barrel and stand against the wall on its horizontal floor. The barrel is spun up and the floor drops away. Riders feel as if they are pinned to the wall by a force something like the gravitational force. This is a fictitious force sensed and used by the riders to explain events in the rotating frame of reference of the barrel. Explain in an inertial frame of reference (Earth is nearly one) what pins the riders to the wall, and identify all of the real forces acting on them

The fact that the Newton's third-law pair of forces are not only equal and oppositely directed but also lie along the line connecting the two objects is sometimes called the strong form of Newton's third law. Why is it important to add that last phrase? Hint: Consider what would happen to these two objects if the forces were offset from each other.

Use an example to describe the difference between tangential and centripetal acceleration.