2. PREVIOUS QUIT NEXT START SLIDE Quiz by Dr. John Dayton Physics Quiz ROTATIONAL EQUILIBRIUM AND DYNAMICS Each question is multiple choice. Select the best response to the question by pressing the button to the left of your choice. If your answer is correct, you will hear an applause. Use the forward and backward buttons at the lower corner of the slides to advance questions.

3. PREVIOUS QUIT NEXT START SLIDE Quiz by Dr. John Dayton 1. What is the effect on an object of an unbalanced torque? C. The object will begin to twist. D. The object will flex or bow. A. The object will have a linear acceleration. B. The object will experience an angular acceleration.

4. PREVIOUS QUIT NEXT START SLIDE Quiz by Dr. John Dayton 2. When is a torque produced? C. When a force acts on an object in conjunction with a moment arm. D. When the moment of inertia is acted on by a force. A. Whenever a force acts on an object. B. When a force acting on an object is directed at the axis of rotation.

5. PREVIOUS QUIT NEXT START SLIDE Quiz by Dr. John Dayton 3. Define the term "line of action" of a force. C. the line connecting the pivot point and the point at which the force is acts D. the line between the pivot and the line along which the force acts A. the line along which a force acts or lies B. the axis of rotation of a rigid body

6. PREVIOUS QUIT NEXT START SLIDE Quiz by Dr. John Dayton 4. What is a moment arm? C. the length of the object D. the length of the line of action A. The distance between the pivot and the point at which the force acts B. the perpendicular distance from the pivot to the line of action of a force

7. PREVIOUS QUIT NEXT START SLIDE Quiz by Dr. John Dayton 5. A force acting on an object is decomposed into two components. The first component points from the point of application of the force directly toward the pivot point. The second component points perpendicular to the first. Which of these components is responsible for the torque produced? C. the second, perpendicular, component D. both components contribute to the net torque A. the first component pointing toward the pivot B. neither component if the force is decomposed

8. PREVIOUS QUIT NEXT START SLIDE Quiz by Dr. John Dayton 6. What are the SI units of torque? C. kg. m 2 /s D. N. m A. J B. kg. m 2

9. PREVIOUS QUIT NEXT START SLIDE Quiz by Dr. John Dayton 7. When an object is in rotational equilibrium, what condition must there be on the applied torques? C. all torques must be clockwise D. all applied torques must be identically zero A. all torques must be counter-clockwise B. their vector sum of all torques must be zero

10. PREVIOUS QUIT NEXT START SLIDE Quiz by Dr. John Dayton 8. Real objects have both size and shape. Through what point does such an object`s weight act? C. the pivot point D. the barrycenter A. the center of gravity B. the center of mass

11. PREVIOUS QUIT NEXT START SLIDE Quiz by Dr. John Dayton 9. A system of objects consists of a mass of 5 kg located at -2 m on the x-axis and another mass of 10 kg located at +4 m on the x-axis. Where is this system`s center of mass? C. +1 m on the x-axis D. +2 m on the x-axis A. +3 m on the x-axis B. at the origin

12. PREVIOUS QUIT NEXT START SLIDE Quiz by Dr. John Dayton 10. Compare and contrast the concepts of the center of mass and the center of gravity. C. If an asymmetric object is turned, its center of gravity changes position but its center of mass is the same. D. All of the above are true. A. They are almost the same point for small objects. B. The center of gravity lies directly below the center of mass which is not dependent on gravity.

13. PREVIOUS QUIT NEXT START SLIDE Quiz by Dr. John Dayton 11. What is moment of inertia? C. Conceptually, moment of inertia is the effective rotational inertia of a rotating body. It depends of the object`s mass and its distribution about the axis of rotation. D. The effective mass of an object that is rotating. A. A temporary increase in effective mass caused by excessive acceleration. B. An additional amount of mass that has to be accounted for due to energy of rotation.

14. PREVIOUS QUIT NEXT START SLIDE Quiz by Dr. John Dayton 12. A small steel ball of 1 kg mass is being spun in a circle at the end of a 1.5 m string. What is the moment of inertia of this system? C. 3.0 kg. m 2 D. 1.0 kg A. 2.25 kg. m 2 B. 1.5 kg. m 2

15. PREVIOUS QUIT NEXT START SLIDE Quiz by Dr. John Dayton 13. What effect will there be if an unbalanced torque of 5 N. m acts on an object whose moment of inertia is 0.5 kg. m 2 ? C. nothing, since it is not rotating D. it will accelerate at 2.5 rad/s 2 A. it will accelerate at 10 rad/s 2 B. it will accelerate at 0.1 rad/s 2

16. PREVIOUS QUIT NEXT START SLIDE Quiz by Dr. John Dayton 14. A disk of mass 2 kg and radius 2 m is traveling 1 m/s and rotating at 3 rad/s. What is the disk’s total kinetic energy? C. 19 J D. 4 J A. 18J B. 1 J

17. PREVIOUS QUIT NEXT START SLIDE Quiz by Dr. John Dayton 15. The orbit of a certain asteroid varies in distance from the Sun from 4 AU to 2 AU. When the asteroid is 4 AU from the sun its speed is v o. What is its speed when it is 2 AU from the Sun? 1 AU = 1.5x10 11 m (astronomical unit) C. 2v O D. 4v o A. v o B. v o /2 When you encounter problems like this it is not enough to guess at the correct answer. You have to know and understand why the correct answer is correct and how to determine it. If you don’t know, ask questions.

18. PREVIOUS QUIT NEXT START SLIDE Quiz by Dr. John Dayton This is the last question of this quiz. 16. A sphere of radius 0.5 m and mass 12 kg rotates about an axis through its center at 20 rad/s. What is the sphere`s angular momentum? C. 1.2 kg. m 2 /s D. 240 kg. m 2 /s A. 5.0 kg. m 2 /s B. 24 kg. m 2 /s