In each of the four situations below an object is experiencing (nearly) uniform circular motion. State what force is providing the centripetal force required to keep the object moving in a circle:  a. A car driving around a track b. A ball being swung on the end of a string c. The moon orbiting the earth d. A rotating wheel 2. Consider the ball being swung around in a circle

14. An object is swung around on a string in a vertical circle, while its speed is slowly increased. At some point, the string breaks. Where in the object's path would this most likely happen? Explain.

A cyclist turn with a radius of 50m at a speed of 10m/s 1. What is the cyclist acceleration? 2. If the cyclist and cycle have a combined mass of 120 kg, what is the force causing them to turn?

9. An early major objection to the idea that the Earth is spinning on its axis was that Earth would turn so fast at the equator that people would be thrown off into space. Show the error in this logic by solving the following problems for a 97.0 kg person standing on the equator where the Earth’s radius is 6378 km. Such a person moves in a circular path due to the Earth’s rotation about its own axis. (a) Determine the centripetal force necessary to keep this person moving in such a fashion. (b) Determine the pull of gravity acting on the person. (c) Determine the normal force acting on the person. (Note: the person is not “at rest” unless the Earth’s surface is the frame of reference. For this problem, let the Earth’s axis be the frame of reference. The person is in motion around the axis even though he is not moving relative to the surface of the Earth.)

QUESTION 1 You swing a mass at the end of a sting in a vertical circle such that  the string remains taut at all times. Which of the following forces is the centripetal force acting on the mass when it is at the bottom of the circular trajectory?   a. the force of gravity   b. the tension in the string   c. the vector sum of the force of gravity and the tension   d. a force other than the force of gravity and the tension     QUESTION 2 A scale with a mass is placed inside an elevator. The scale reading will be the same when the elevator is moving at a constant velocity as when it is stopped.   True  False

5. When you whirl a ball on a cord in a vertical circle, you find a critical speed at the top for which the tension in the cord is zero. This is because the force of gravity on the object itself supplies the necessary centripetal force. How slowly can you swing a 2.5 kg ball like this so that it will just follow a circle with a radius of 1.5 m?

1. Which of the following is an example of circular motion in which there is no centripetal force pushing or pulling on the object? a) The moon orbiting the earth. b) A ball being twirled about on a string.   c) An airplane circling an airport while it waits to land.   d) All circular motion requires a centripetal force of some kind.     2. A race car speeds around the curved end of a racetrack. What provides the centripetal force necessary to for the car to move in the curved path?   a) The gravitation force of the earth. b) The air resistance on the car. c) The friction between the tires and track. d) The engine of the car.

Two balls, X and Y, are spun at a velocity of 6.5 m/s in a horizontal circle on the path shown below. Ball X has a mass of 1.3 kg, and ball Y has a mass of 0.81 kg. Which statement best describes the centripetal acceleration and centripetal forces on the balls? A. Both balls will experience equal centripetal force and centripetal acceleration. B. Ball X will experience greater centripetal force and greater centripetal acceleration. C. Ball Y will experience greater centripetal force, but ball X will experience greater centripetal acceleration. D. Both balls will experience the same centripetal acceleration, but ball X will experience greater centripetal force.

8. How is it possible that a body moves at a constant speed and is still in accelerating motion? 9. When a car is going around a circular track with constant speed, what provides the centripetal force necessary for circular motion?

5. Determine the source of centripetal force in the following examples. a. Earth orbiting around the sun. b. Car moving along a circular track. c. Bucket attached to a rope, spun in a horizontal circle.