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Halliday/Resnick/Walker Fundamentals of Physics 8 th edition

Halliday/Resnick/Walker Fundamentals of Physics 8 th edition. Classroom Response System Questions. Chapter 6 Forces and Motion II. Interactive Lecture Questions.

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Halliday/Resnick/Walker Fundamentals of Physics 8 th edition

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  1. Halliday/Resnick/WalkerFundamentals of Physics 8th edition • Classroom Response System Questions Chapter 6 Forces and Motion II Interactive Lecture Questions

  2. 6.3.1. Jennifer is pushing a heavy box up a rough inclined surface at a constant speed by applying a horizontal force as shown in the drawing. The coefficient of kinetic friction for the box on the inclined surface is k. Which one of the following expressions correctly determines the normal force on the box? a) b) c) d) e)

  3. 6.3.1. Jennifer is pushing a heavy box up a rough inclined surface at a constant speed by applying a horizontal force as shown in the drawing. The coefficient of kinetic friction for the box on the inclined surface is k. Which one of the following expressions correctly determines the normal force on the box? a) b) c) d) e)

  4. 6.3.2. Three pine blocks, each with identical mass, are sitting on a rough surface as shown. If the same horizontal force is applied to each block, which one of the following statements is false? a) The coefficient of kinetic friction is the same for all three blocks. b) The magnitude of the force of kinetic friction is greater for block 3. c) The normal force exerted by the surface is the same for all three blocks. d) Block 3 has the greatest apparent area in contact with the surface. e) If the horizontal force is the minimum to start block 1 moving, then that same force could be used to start block 2 or block 3 moving.

  5. 6.3.2. Three pine blocks, each with identical mass, are sitting on a rough surface as shown. If the same horizontal force is applied to each block, which one of the following statements is false? a) The coefficient of kinetic friction is the same for all three blocks. b) The magnitude of the force of kinetic friction is greater for block 3. c) The normal force exerted by the surface is the same for all three blocks. d) Block 3 has the greatest apparent area in contact with the surface. e) If the horizontal force is the minimum to start block 1 moving, then that same force could be used to start block 2 or block 3 moving.

  6. 6.3.3. A crate of mass m is at rest on a horizontal frictionless surface. Another identical crate is placed on top of it. Assuming that there is no slipping of the top crate as a horizontal force is applied to the bottom crate, determine an expression for the magnitude of the static frictional force acting on the top crate. a) b) c) d) e)

  7. 6.3.3. A crate of mass m is at rest on a horizontal frictionless surface. Another identical crate is placed on top of it. Assuming that there is no slipping of the top crate as a horizontal force is applied to the bottom crate, determine an expression for the magnitude of the static frictional force acting on the top crate. a) b) c) d) e)

  8. 6.3.4. A crate of mass m is at rest on a horizontal frictionless surface. Another identical crate is placed on top of it. Assuming a horizontal force is applied to the bottom crate, determine an expression for the minimum static coefficient of friction so that the top crate does not slip. a) b) c) d) e)

  9. 6.3.4. A crate of mass m is at rest on a horizontal frictionless surface. Another identical crate is placed on top of it. Assuming a horizontal force is applied to the bottom crate, determine an expression for the minimum static coefficient of friction so that the top crate does not slip. a) b) c) d) e)

  10. 6.3.5. On a rainy evening, a truck is driving along a straight, level road at 25 m/s. The driver panics when a deer runs onto the road and locks the wheels while braking. If the coefficient of friction for the wheel/road interface is 0.68, how far does the truck slide before it stops? a) 55 m b) 47 m c) 41 m d) 36 m e) 32 m

  11. 6.3.5. On a rainy evening, a truck is driving along a straight, level road at 25 m/s. The driver panics when a deer runs onto the road and locks the wheels while braking. If the coefficient of friction for the wheel/road interface is 0.68, how far does the truck slide before it stops? a) 55 m b) 47 m c) 41 m d) 36 m e) 32 m

  12. 6.3.6. Jake bought a new dog and is carrying a new dog house on the flatbed of his brand new pickup truck. Jake isn’t sure if he should tie the house down, but he doesn’t want it to scratch the paint if it should slide during braking. During the trip home, Jake will travel along straight, level roads and have to stop from a maximum speed of 21 m/s in a distance of 29 m. What is the minimum coefficient of static friction between the dog house and the flatbed that is required to prevent it from sliding? Compare your answer to the actual coefficient of static friction of 0.35 to determine if the dog house should be tied down. a) 0.22, no need to tie the house down b) 0.30, no need to tie the house down c) 0.35, he may want to tie it down…just in case d) 0.56, the house needs to be tied down e) 0.78, the house needs to be tied down

  13. 6.3.6. Jake bought a new dog and is carrying a new dog house on the flatbed of his brand new pickup truck. Jake isn’t sure if he should tie the house down, but he doesn’t want it to scratch the paint if it should slide during braking. During the trip home, Jake will travel along straight, level roads and have to stop from a maximum speed of 21 m/s in a distance of 29 m. What is the minimum coefficient of static friction between the dog house and the flatbed that is required to prevent it from sliding? Compare your answer to the actual coefficient of static friction of 0.35 to determine if the dog house should be tied down. a) 0.22, no need to tie the house down b) 0.30, no need to tie the house down c) 0.35, he may want to tie it down…just in case d) 0.56, the house needs to be tied down e) 0.78, the house needs to be tied down

  14. 6.3.7. A block of mass m is pressed against a wall with an initial force and the block is at rest. The coefficient of static friction for the block against the wall is equal to 0.5. The coefficient of kinetic friction is less than the coefficient of static friction. If the force is equal to the weight of the block, which one of the following statements is true? a) The block will continue to remain at rest because the force of static friction is two times the weight of the block. b) The block will slide down the wall because the force of static friction is only equal to one-half of the block’s weight. c) The block will accelerate at 9.8 m/s2 down the wall. d) The block will slide down the wall at constant speed. e) The block will accelerate at less than 4.9 m/s2 down the wall.

  15. 6.3.7. A block of mass m is pressed against a wall with an initial force and the block is at rest. The coefficient of static friction for the block against the wall is equal to 0.5. The coefficient of kinetic friction is less than the coefficient of static friction. If the force is equal to the weight of the block, which one of the following statements is true? a) The block will continue to remain at rest because the force of static friction is two times the weight of the block. b) The block will slide down the wall because the force of static friction is only equal to one-half of the block’s weight. c) The block will accelerate at 9.8 m/s2 down the wall. d) The block will slide down the wall at constant speed. e) The block will accelerate at less than 4.9 m/s2 down the wall.

  16. 6.3.8. A 1.0 kg block is placed against a wall and is held stationary by a force of 8.0 N applied at a 45° angle as shown in the drawing. What is the magnitude of the friction force? a) 3.7 N b) 4.1 N c) 5.8 N d) 7.0 N e) 8.0 N

  17. 6.3.8. A 1.0 kg block is placed against a wall and is held stationary by a force of 8.0 N applied at a 45° angle as shown in the drawing. What is the magnitude of the friction force? a) 3.7 N b) 4.1 N c) 5.8 N d) 7.0 N e) 8.0 N

  18. 6.3.9. A rancher puts a hay bail into the back of her SUV. Later, she drives around an unbanked curve with a radius of 48 m at a speed of 16 m/s. What is the minimum coefficient of static friction for the hay bail on the floor of the SUV so that the hay bail does not slide while on the curve? a) This cannot be determined without knowing the mass of the hay bail. b) 0.17 c) 0.33 d) 0.42 e) 0.54

  19. 6.3.9. A rancher puts a hay bail into the back of her SUV. Later, she drives around an unbanked curve with a radius of 48 m at a speed of 16 m/s. What is the minimum coefficient of static friction for the hay bail on the floor of the SUV so that the hay bail does not slide while on the curve? a) This cannot be determined without knowing the mass of the hay bail. b) 0.17 c) 0.33 d) 0.42 e) 0.54

  20. 6.4.1. Consider the following situations: (i) A minivan is following a hairpin turn on a mountain road at a constant speed of twenty miles per hour. (ii) A parachutist is descending at a constant speed 10 m/s. (iii) A heavy crate has been given a quick shove and is now sliding across the floor. (iv) Jenny is swinging back and forth on a swing at the park. (v) A football that was kicked is flying through the goal posts. (vi) A plucked guitar string vibrates at a constant frequency. In which one of these situations does the object or person experience zero acceleration? a) i only b) ii only c) iii and iv only d) iv, v, and vi only e) all of the situations

  21. 6.4.1. Consider the following situations: (i) A minivan is following a hairpin turn on a mountain road at a constant speed of twenty miles per hour. (ii) A parachutist is descending at a constant speed 10 m/s. (iii) A heavy crate has been given a quick shove and is now sliding across the floor. (iv) Jenny is swinging back and forth on a swing at the park. (v) A football that was kicked is flying through the goal posts. (vi) A plucked guitar string vibrates at a constant frequency. In which one of these situations does the object or person experience zero acceleration? a) i only b) ii only c) iii and iv only d) iv, v, and vi only e) all of the situations

  22. 6.4.2. A sky diver jumps from a flying airplane and falls for several seconds before she reaches terminal velocity. She then opens her parachute, reaches a new terminal velocity, and continues her descent to the ground. Which one of the following graphs of the drag force versus time best represents this situation?

  23. 6.4.2. A sky diver jumps from a flying airplane and falls for several seconds before she reaches terminal velocity. She then opens her parachute, reaches a new terminal velocity, and continues her descent to the ground. Which one of the following graphs of the drag force versus time best represents this situation?

  24. 6.4.3. A feather and a minivan are dropped vertically downward from a height of twenty meters and both are subject to air drag as they fall. The minivan reaches the ground much faster than the feather. Which one of the following statements concerning this situation is true, if any? a) The minivan has a larger terminal velocity than the feather because it experiences less air resistance than the feather. b) The minivan encounters a smaller force of air resistance than the feather and falls faster. c) Each object experiences the same amount of air drag, but the minivan experiences the greatest force of gravity. d) The feather experiences more air drag than the minivan and has a smaller terminal velocity. e) None of the above statements are true.

  25. 6.4.3. A feather and a minivan are dropped vertically downward from a height of twenty meters and both are subject to air drag as they fall. The minivan reaches the ground much faster than the feather. Which one of the following statements concerning this situation is true, if any? a) The minivan has a larger terminal velocity than the feather because it experiences less air resistance than the feather. b) The minivan encounters a smaller force of air resistance than the feather and falls faster. c) Each object experiences the same amount of air drag, but the minivan experiences the greatest force of gravity. d) The feather experiences more air drag than the minivan and has a smaller terminal velocity. e) None of the above statements are true.

  26. 6.4.4. A light ping-pong ball and a heavy rubber ball of exactly the same size are each launched at the same angle and initial velocity, but the rubber ball goes much farther than the ping-pong ball. Which one of the following statements best explains this result? a) The ping-pong ball weighs less, so the acceleration due to gravity is smaller for it. b) The drag force on the ping-pong ball is larger. c) The ping-pong ball has less momentum. d) The ping-pong ball has less mass, so the same drag force slows the ping-pong ball down more. e) The ping-pong ball has a smaller moment of inertia since it is hollow and weighs less.

  27. 6.4.4. A light ping-pong ball and a heavy rubber ball of exactly the same size are each launched at the same angle and initial velocity, but the rubber ball goes much farther than the ping-pong ball. Which one of the following statements best explains this result? a) The ping-pong ball weighs less, so the acceleration due to gravity is smaller for it. b) The drag force on the ping-pong ball is larger. c) The ping-pong ball has less momentum. d) The ping-pong ball has less mass, so the same drag force slows the ping-pong ball down more. e) The ping-pong ball has a smaller moment of inertia since it is hollow and weighs less.

  28. 6.5.1. A ball is whirled on the end of a string in a horizontal circle of radius R at constant speed v. By which one of the following means can the centripetal acceleration of the ball be increased by a factor of two? a) Keep the radius fixed and increase the period by a factor of two. b) Keep the radius fixed and decrease the period by a factor of two. c) Keep the speed fixed and increase the radius by a factor of two. d) Keep the speed fixed and decrease the radius by a factor of two. e) Keep the radius fixed and increase the speed by a factor of two.

  29. 6.5.1. A ball is whirled on the end of a string in a horizontal circle of radius R at constant speed v. By which one of the following means can the centripetal acceleration of the ball be increased by a factor of two? a) Keep the radius fixed and increase the period by a factor of two. b) Keep the radius fixed and decrease the period by a factor of two. c) Keep the speed fixed and increase the radius by a factor of two. d) Keep the speed fixed and decrease the radius by a factor of two. e) Keep the radius fixed and increase the speed by a factor of two.

  30. 6.5.2. A steel ball is whirled on the end of a chain in a horizontal circle of radius R with a constant period T. If the radius of the circle is then reduced to 0.75R, while the period remains T, what happens to the centripetal acceleration of the ball? a) The centripetal acceleration increases to 1.33 times its initial value. b) The centripetal acceleration increases to 1.78 times its initial value. c) The centripetal acceleration decreases to 0.75 times its initial value. d) The centripetal acceleration decreases to 0.56 times its initial value. e) The centripetal acceleration does not change.

  31. 6.5.2. A steel ball is whirled on the end of a chain in a horizontal circle of radius R with a constant period T. If the radius of the circle is then reduced to 0.75R, while the period remains T, what happens to the centripetal acceleration of the ball? a) The centripetal acceleration increases to 1.33 times its initial value. b) The centripetal acceleration increases to 1.78 times its initial value. c) The centripetal acceleration decreases to 0.75 times its initial value. d) The centripetal acceleration decreases to 0.56 times its initial value. e) The centripetal acceleration does not change.

  32. 6.5.3. A boy is whirling a stone at the end of a string around his head. The string makes one complete revolution every second, and the tension in the string is FT. The boy increases the speed of the stone, keeping the radius of the circle unchanged, so that the string makes two complete revolutions per second. What happens to the tension in the sting? a) The tension increases to four times its original value. b) The tension increases to twice its original value. c) The tension is unchanged. d) The tension is reduced to one half of its original value. e) The tension is reduced to one fourth of its original value.

  33. 6.5.3. A boy is whirling a stone at the end of a string around his head. The string makes one complete revolution every second, and the tension in the string is FT. The boy increases the speed of the stone, keeping the radius of the circle unchanged, so that the string makes two complete revolutions per second. What happens to the tension in the sting? a) The tension increases to four times its original value. b) The tension increases to twice its original value. c) The tension is unchanged. d) The tension is reduced to one half of its original value. e) The tension is reduced to one fourth of its original value.

  34. 6.5.4. An aluminum rod is designed to break when it is under a tension of 600 N. One end of the rod is connected to a motor and a 12-kg spherical object is attached to the other end. When the motor is turned on, the object moves in a horizontal circle with a radius of 6.0 m. If the speed of the motor is continuously increased, at what speed will the rod break? Ignore the mass of the rod for this calculation. a) 11 m/s b) 17 m/s c) 34 m/s d) 88 m/s e) 3.0 × 102 m/s

  35. 6.5.4. An aluminum rod is designed to break when it is under a tension of 600 N. One end of the rod is connected to a motor and a 12-kg spherical object is attached to the other end. When the motor is turned on, the object moves in a horizontal circle with a radius of 6.0 m. If the speed of the motor is continuously increased, at what speed will the rod break? Ignore the mass of the rod for this calculation. a) 11 m/s b) 17 m/s c) 34 m/s d) 88 m/s e) 3.0 × 102 m/s

  36. 6.5.5. A ball is attached to a string and whirled in a horizontal circle. The ball is moving in uniform circular motion when the string separates from the ball (the knot wasn’t very tight). Which one of the following statements best describes the subsequent motion of the ball? a) The ball immediately flies in the direction radially outward from the center of the circular path the ball had been following. b) The ball continues to follow the circular path for a short time, but then it gradually falls away. c) The ball gradually curves away from the circular path it had been following. d) The ball immediately follows a linear path away from, but not tangent to the circular path it had been following. e) The ball immediately follows a line that is tangent to the circular path the ball had been following

  37. 6.5.5. A ball is attached to a string and whirled in a horizontal circle. The ball is moving in uniform circular motion when the string separates from the ball (the knot wasn’t very tight). Which one of the following statements best describes the subsequent motion of the ball? a) The ball immediately flies in the direction radially outward from the center of the circular path the ball had been following. b) The ball continues to follow the circular path for a short time, but then it gradually falls away. c) The ball gradually curves away from the circular path it had been following. d) The ball immediately follows a linear path away from, but not tangent to the circular path it had been following. e) The ball immediately follows a line that is tangent to the circular path the ball had been following

  38. 6.5.6. Complete the following statement: The maximum speed at which a car can safely negotiate an unbanked curve depends on all of the following factors except a) the coefficient of kinetic friction between the road and the tires. b) the coefficient of static friction between the road and the tires. c) the acceleration due to gravity. d) the diameter of the curve. e) the ratio of the static frictional force between the road and the tires and the normal force exerted on the car.

  39. 6.5.6. Complete the following statement: The maximum speed at which a car can safely negotiate an unbanked curve depends on all of the following factors except a) the coefficient of kinetic friction between the road and the tires. b) the coefficient of static friction between the road and the tires. c) the acceleration due to gravity. d) the diameter of the curve. e) the ratio of the static frictional force between the road and the tires and the normal force exerted on the car.

  40. 6.5.7. A 1000-kg car travels along a straight portion of highway at a constant velocity of 10 m/s, due east. The car then encounters an unbanked curve of radius 50 m. The car follows the curve traveling at a constant speed of 10 m/s while the direction of the car changes from east to south. What is the magnitude of the frictional force between the tires and the road as the car negotiates the unbanked curve? a) 500 N b) 1000 N c) 2000 N d) 5000 N e) 10 000 N

  41. 6.5.7. A 1000-kg car travels along a straight portion of highway at a constant velocity of 10 m/s, due east. The car then encounters an unbanked curve of radius 50 m. The car follows the curve traveling at a constant speed of 10 m/s while the direction of the car changes from east to south. What is the magnitude of the frictional force between the tires and the road as the car negotiates the unbanked curve? a) 500 N b) 1000 N c) 2000 N d) 5000 N e) 10 000 N

  42. 6.5.8. A space station is designed in the shape of a large, hollow donut that is uniformly rotating. The outer radius of the station is 460 m. With what period must the station rotate so that a person sitting on the outer wall experiences “artificial gravity,” i.e. an acceleration of 9.8 m/s2? a) 43 s b) 76 s c) 88 s d) 110 s e) 230 s

  43. 6.5.8. A space station is designed in the shape of a large, hollow donut that is uniformly rotating. The outer radius of the station is 460 m. With what period must the station rotate so that a person sitting on the outer wall experiences “artificial gravity,” i.e. an acceleration of 9.8 m/s2? a) 43 s b) 76 s c) 88 s d) 110 s e) 230 s

  44. 6.5.9. At a circus, a clown on a motorcycle with a mass M travels along a horizontal track and enters a vertical circle of radius r. Which one of the following expressions determines the minimum speed that the motorcycle must have at the top of the track to remain in contact with the track? a) b) c) v = gR d) v = 2gR e) v = MgR

  45. 6.5.9. At a circus, a clown on a motorcycle with a mass M travels along a horizontal track and enters a vertical circle of radius r. Which one of the following expressions determines the minimum speed that the motorcycle must have at the top of the track to remain in contact with the track? a) b) c) v = gR d) v = 2gR e) v = MgR

  46. 6.5.10. A ball on the end of a rope is moving in a vertical circle near the surface of the earth. Point A is at the top of the circle; C is at the bottom. Points B and D are exactly halfway between A and C. Which one of the following statements concerning the tension in the rope is true? a) The tension is smallest at point A. b) The tension is smallest at point C. c) The tension is smallest at both points B and D. d) The tension is the same at points A and C. e) The tension is the same at all four points.

  47. 6.5.10. A ball on the end of a rope is moving in a vertical circle near the surface of the earth. Point A is at the top of the circle; C is at the bottom. Points B and D are exactly halfway between A and C. Which one of the following statements concerning the tension in the rope is true? a) The tension is smallest at point A. b) The tension is smallest at point C. c) The tension is smallest at both points B and D. d) The tension is the same at points A and C. e) The tension is the same at all four points.

  48. 6.5.11. Imagine you are swinging a bucket by the handle around in a circle that is nearly level with the ground (a horizontal circle). What is the force, the physical force, holding the bucket in a circular path? a) the centripetal force b) the centrifugal force c) your hand on the handle d) gravitational force e) None of the above are correct.

  49. 6.5.11. Imagine you are swinging a bucket by the handle around in a circle that is nearly level with the ground (a horizontal circle). What is the force, the physical force, holding the bucket in a circular path? a) the centripetal force b) the centrifugal force c) your hand on the handle d) gravitational force e) None of the above are correct.

  50. 6.5.12. Imagine you are swinging a bucket by the handle around in a circle that is nearly level with the ground (a horizontal circle). Now imagine there's a ball in the bucket. What keeps the ball moving in a circular path? a) contact force of the bucket on the ball b) contact force of the ball on the bucket c) gravitational force on the ball d) the centripetal force e) the centrifugal force

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