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Clicker Review: Newton’s Laws

Clicker Review: Newton’s Laws. http://www.flickr.com/photos/alertjean/3196344683/ . Newton's law of inertia does not describe the behavior of objects. in inertial frames of reference. moving with constant velocity relative to a given frame of reference.

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Clicker Review: Newton’s Laws

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  1. Clicker Review: Newton’s Laws http://www.flickr.com/photos/alertjean/3196344683/

  2. Newton's law of inertia does not describe the behavior of objects • in inertial frames of reference. • moving with constant velocity relative to a given frame of reference. • at rest relative to a given inertial frame of reference. • moving in accelerated frames of reference. • moving in a straight line at constant speed relative to a given inertial reference frame.

  3. Newton's law of inertia does not describe the behavior of objects • in inertial frames of reference. • moving with constant velocity relative to a given frame of reference. • at rest relative to a given inertial frame of reference. • moving in accelerated frames of reference. • moving in a straight line at constant speed relative to a given inertial reference frame.

  4. When Newton's first law of motion is mentioned, you should immediately think of • F = ma • action-and-reaction forces. • inertia. • gravitational forces. • centripetal acceleration.

  5. When Newton's first law of motion is mentioned, you should immediately think of • F = ma • action-and-reaction forces. • inertia. • gravitational forces. • centripetal acceleration.

  6. A body moves with constant speed in a straight line. Which of the following statements must be true? • No force acts on the body. • A single constant force acts on the body in the direction of motion. • A single constant force acts on the body in the direction opposite to the motion. • A net force of zero acts on the body. • A constant net force acts on the body in the direction of motion.

  7. A body moves with constant speed in a straight line. Which of the following statements must be true? • No force acts on the body. • A single constant force acts on the body in the direction of motion. • A single constant force acts on the body in the direction opposite to the motion. • A net force of zero acts on the body. • A constant net force acts on the body in the direction of motion.

  8. A force accelerates a body of mass M. The same force applied to a second body produces three times the acceleration. What is the mass of the second body? • M • 3M • M/3 • 9M • M/9

  9. A force accelerates a body of mass M. The same force applied to a second body produces three times the acceleration. What is the mass of the second body? • M • 3M • M/3 • 9M • M/9

  10. A person of weight w is in an upward-moving elevator when the cable suddenly breaks. What is the person's apparent weight immediately after the elevator starts to fall? • w • greater than w • less than w, but not zero • 9.81w • zero

  11. A person of weight w is in an upward-moving elevator when the cable suddenly breaks. What is the person's apparent weight immediately after the elevator starts to fall? • w • greater than w • less than w, but not zero • 9.81w • zero

  12. Participant Scores

  13. Fastest Responders (in seconds)

  14. The acceleration due to gravity on the Moon is only about 1/6 of that on Earth. An astronaut whose weight on Earth is 600 N travels to the lunar surface. His mass as measured on the Moon is approximately • 600 kg • 100 kg • 60 kg • 10.0 kg • 360 kg

  15. The acceleration due to gravity on the Moon is only about 1/6 of that on Earth. An astronaut whose weight on Earth is 600 N travels to the lunar surface. His mass as measured on the Moon is approximately • 600 kg • 100 kg • 60 kg • 10.0 kg • 360 kg

  16. If a force F is required to extend a spring by 20 cm, what force is required to extend it by 30 cm? (Assume small displacements, so that Hooke’s Law applies.) • F • (2/3)F • (3/2)F • 600F • (3/5)F

  17. If a force F is required to extend a spring by 20 cm, what force is required to extend it by 30 cm? (Assume small displacements, so that Hooke’s Law applies.) • F • (2/3)F • (3/2)F • 600F • (3/5)F

  18. Which of the free-body diagrams represents the block sliding down a frictionless inclined plane? (Neglect air resistance.) • A • B • C • D • E

  19. Which of the free-body diagrams represents the block sliding down a frictionless inclined plane? (Neglect air resistance.)

  20. Fastest Responders (in seconds)

  21. Participant Scores

  22. A box sits on an inclined plane without sliding. As the angle of inclination increases, the normal force • increases. • decreases. • does not change. • is directed upward. • is directed in the direction of the gravitational force.

  23. A box sits on an inclined plane without sliding. As the angle of inclination increases, the normal force • increases. • decreases. • does not change. • is directed upward. • is directed in the direction of the gravitational force.

  24. Is the net force an actual force? • Yes • No

  25. Is the net force an actual force? • Yes • No

  26. As you stand facing a friend, place your palms against your friend’s palms and push. Can your friend exert a force on you if you do not exert a force back? Try it! • Yes • No

  27. As you stand facing a friend, place your palms against your friend’s palms and push. Can your friend exert a force on you if you do not exert a force back? Try it! • Yes • No

  28. Fastest Responders (in seconds)

  29. Participant Scores

  30. Friction

  31. Four identical blocks are moving on a surface for which the coefficient of kinetic friction between each block and the surface is µk. The velocity of each block is indicated by the vector on the block. For which block is the force of friction between the surface and the block greatest? • 1 • 2 • 3 • 4 • The force of friction is the same for all blocks.

  32. Four identical blocks are moving on a surface for which the coefficient of kinetic friction between each block and the surface is µk. The velocity of each block is indicated by the vector on the block. For which block is the force of friction between the surface and the block greatest? 1 2 3 4 The force of friction is the same for all blocks.

  33. A block of mass m is at rest on an inclined plane that makes an angle of 30º with the horizontal, as shown in the figure. Which of the following statements about the force of static friction is true? • fs > mg • fs > mg cos 30º • fs = mg cos 30º • fs = mg sin 30º • None of the statements is true.

  34. A block of mass m is at rest on an inclined plane that makes an angle of 30º with the horizontal, as shown in the figure. Which of the following statements about the force of static friction is true? fs > mg fs > mg cos 30º fs = mg cos 30º fs = mg sin 30º None of the statements is true.

  35. A block of wood is pulled by a horizontal string across a rough surface at a constant velocity with a force of 20 N. The coefficient of kinetic friction between the surfaces is 0.3. The force of friction is • impossible to determine without knowing the mass of the block. • impossible to determine without knowing the speed of the block. • 0.3 N. • 6 N. • 20 N.

  36. A block of wood is pulled by a horizontal string across a rough surface at a constant velocity with a force of 20 N. The coefficient of kinetic friction between the surfaces is 0.3. The force of friction is impossible to determine without knowing the mass of the block. impossible to determine without knowing the speed of the block. 0.3 N. 6 N. 20 N.

  37. The SI units for the coefficient of friction are • newtons per meter. • meters. • newtons. • newtons times meters. • None of these is correct; the coefficient of friction is dimensionless.

  38. The SI units for the coefficient of friction are newtons per meter. meters. newtons. newtons times meters. None of these is correct; the coefficient of friction is dimensionless.

  39. Which free-body diagram best represents the forces acting on the student sliding down a rough incline? • A • B • C • D • E

  40. Which free-body diagram best represents the forces acting on the student sliding down a rough incline?

  41. Circular motion

  42. An object traveling in a circle at constant speed • is moving with constant velocity. • may be slowing down or picking up speed. • experiences no acceleration. • experiences an acceleration toward the center of the circle. • none of the above

  43. An object traveling in a circle at constant speed is moving with constant velocity. may be slowing down or picking up speed. experiences no acceleration. experiences an acceleration toward the center of the circle. none of the above

  44. A car going around a curve of radius R at a speed V experiences a centripetal acceleration ac. What is its acceleration if it goes around a curve of radius 3R at a speed of 2V? • (2/3)ac • (4/3)ac • (2/9)ac • (9/2)ac • (3/2)ac

  45. A car going around a curve of radius R at a speed V experiences a centripetal acceleration ac. What is its acceleration if it goes around a curve of radius 3R at a speed of 2V? (2/3)ac (4/3)ac (2/9)ac (9/2)ac (3/2)ac

  46. The figure shows a top view of a ball on the end of a string traveling counterclockwise in a circular path. The speed of the ball is constant. If the string should break at the instant shown, the path that the ball would follow is • 1 • 2 • 3 • 4 • impossible to tell from the given information.

  47. The figure shows a top view of a ball on the end of a string traveling counterclockwise in a circular path. The speed of the ball is constant. If the string should break at the instant shown, the path that the ball would follow is 1 2 3 4 impossible to tell from the given information.

  48. The figure shows a top view of a ball on the end of a string traveling counterclockwise in a circular path. Assume that air resistance is negligible. Which free-body diagram best represents the net force acting on the ball? • A • B • C • D • E

  49. The figure shows a top view of a ball on the end of a string traveling counterclockwise in a circular path. Assume that air resistance is negligible. Which vector best represents the acceleration of the ball?

  50. Fastest Responders (in seconds)

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