About the Exam on OCTOBER 11

Types of problems for this exam are: For your preparation pleasure:

Multiple-Choice

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6. One year is about ________ seconds while one day is exactly ________ seconds.

a. 3.16 × 107, 86 400
b. 5.26 × 105, 86 400
c. 3.16 × 107, 8 640
d. 1.04 × 106, 36 000correct

11. Which expression is dimensionally consistent with an expression that would yield a value for time-1?(v is velocity, x is distance, and t is time)
a. v/xcorrect
b. v/x
c. x/t
d. vt

12. If the displacement of an object, x, is related to velocity, v, according to the relation x = Av, the constant, A, has the dimension of which of the following?
a. acceleration
b. length
c. timecorrect
d. area

14. If a is acceleration, v is velocity, x is position, and t is time, then which equation is not dimensionally correct?
a. t = x/v
b. a = v/x
c. v = a/tcorrect
d. t = 2x/a

17. Which one of the choices below represents the preferred practice regarding significant figures when adding the following: 12.4 + 11 + 67.37 + 4.201?
a. 94.971
b. 94.97
c. 95.0
d. 95correct

18. Which one of the choices below represents the preferred practice regarding significant figures when multiplying the following: 10.5 8.8 3.14?
a. 290correct
b. 290.136
c. 290.1
d. 300

28. A cement truck can pour 20 cubic yards of cement per hour. Express this in ft/min. (1 yard = 3 ft)
a. 1/3 ft/min
b. 1.0 ft/min
c. 3 ft/min
d. 9 ft/mincorrect

31. The mass of the sun is 2.0 × 1030 kg, and the mass of a hydrogen atom is 1.67 × 10-27 kg. If we assume that the sun is mostly composed of hydrogen, how many atoms are there in the sun?
a. 1.2 1056 atoms
b. 3.4 1056 atoms
c. 1.2 1057 atomscorrect
d. 2.4 1057 atoms

34. A physics class in a large lecture hall has 150 students. Estimate the total mass of the students in kg.
a. 102
b. 103
c. 104correct
d. 105

49. A circle has an area of 2.0 m2. A second circle has double the radius of the first. The area of the second circle is _____ times that of the first.
a. 0.50
b. 2.0
c. 4.0correct
d. 8.0

3. A truck moves 70 m east, then moves 120 m west, and finally moves east again a distance of 90 m. If east is chosen as the positive direction, what is the truck's resultant displacement?
a. 40 mcorrect
b. - 40 m
c. 280 m
d. -280 m

4. Which of the following is not a vector quantity?
a. temperaturecorrect
b. velocity
c. acceleration
d. displacement

9. A bird, accelerating from rest at a constant rate, experiences a displacement of 28 m in 11 s. What is the average velocity?
a. 1.7 m/s
b. 2.5 m/scorrect
c. 3.4 m/s
d. zero

10. A cheetah can run at approximately 100 km/hr and a gazelle at 80.0 km/hr. If both animals are running at full speed, with the gazelle 70.0 m ahead, how long before the cheetah catches its prey?
a. 12.6 scorrect
b. 25.2 s
c. 6.30 s
d. 10.7 s

11. A cheetah can maintain its maximum speed of 100 km/hr for 30.0 seconds. What minimum distance must a gazelle running 80.0 km/hr be ahead of the cheetah to escape?
a. 100 m
b. 167 mcorrect
c. 70.0 m
d. 83.0 m

12. Jeff throws a ball straight up. For which situation is the vertical velocity zero?
a. on the way up
b. at the topcorrect
c. on the way back down
d. none of the above

17. On a position versus time graph, the slope of the straight line joining two points on the plotted curve that are separated in time by the interval t, is which of the following quantities?

a. average steepness
b. average velocitycorrect
c. instantaneous velocity
d. average acceleration

18. A European sports car dealer claims that his car will accelerate at a constant rate from rest to 100 km/hr in 8.00 s. If so, what is the acceleration? (Hint: First convert speed to m/s.)
a. 3.47 m/s2correct
b. 6.82 m/s2
c. 11.4 m/s2
d. 17.4 m/s2

20. An x vs. t graph is drawn for a ball moving in one direction. The graph starts at the origin and at t = 5 s the velocity of the ball is zero. We can be positive that at t = 5 s,
a. the slope of the curve is non zero.
b. the ball has stopped.correct
c. the acceleration is constant.
d. the curve is at x = 0, t = 0.

21. A v vs. t graph is drawn for a ball moving in one direction. The graph starts at the origin and at t = 5 s the acceleration of the ball is zero. We know that at t = 5 s,
a. the slope of the curve is non zero.
b. the velocity of the ball is not changing.correct
c. the curve is not crossing the time axis.
d. the curve is at v = 0, t = 0.

22. The value of an object's acceleration may be characterized in equivalent words by which of the following?
a. displacement
b. rate of change of displacement
c. velocity
d. rate of change of velocitycorrect

26. A strobe photograph shows equally spaced images of a car moving along a straight road. If the time intervals between images is constant, which of the following cannot be positive?

a. the speed of the car
b. the average velocity of the car
c. the acceleration of the carcorrect
d. the direction of motion of the car

27. A strobe photograph of a car moving along a straight road shows the interval between each successive image to be diminishing. If the direction of motion of the car is taken as positive, which of the following are negative?
a. the speed of the car
b. the average velocity of the car
c. the average acceleration of the carcorrect
d. all of the above

28. A ball is pushed with an initial velocity of 4.0 m/s. The ball rolls down a hill with a constant acceleration of 1.6 m/s2. The ball reaches the bottom of the hill in 8.0 s. What is the ball's velocity at the bottom of the hill?
a. 10 m/s
b. 12 m/s
c. 16 m/s
d. 17 m/scorrect

30. A vehicle designed to operate on a drag strip accelerates from zero to 30 m/s while undergoing a straight line path displacement of 45 m. What is the vehicle's acceleration if its value may be assumed to be constant?
a. 2.0 m/s2
b. 5.0 m/s2
c. 10 m/s2correct
d. 15 m/s2

31. When a drag strip vehicle reaches a velocity of 60 m/s, it begins a negative acceleration by releasing a drag chute and applying its brakes. While reducing its velocity back to zero, its acceleration along a straight line path is a constant 7.5 m/s2. What displacement does it undergo during this deceleration period?
a. 40 m
b. 80 m
c. 160 m
d. 240 mcorrect

37. A drag racer starts from rest and accelerates at 10 m/s2 for the entire distance of 400 m (1/4 mile). What is the velocity of the race car at the end of the run?
a. 45 m/s
b. 89 m/scorrect
c. 130 m/s
d. 180 m/s

38. A Cessna aircraft has a lift off speed of 120 km/hr. What minimum constant acceleration does this require if the aircraft is to be airborne after a take off run of 240 m?
a. 2.31 m/s2correct
b. 3.63 m/s2
c. 4.63 m/s2
d. 5.55 m/s2

42. A rock is thrown straight up with an initial velocity of 24.5 m/s.What maximum height will the rock reach before starting to fall downward? (Take acceleration due to gravity as 9.80 m/s2.)
a. 9.80 m
b. 19.6 m
c. 24.5 m
d. 30.6 mcorrect

43. A rock is thrown straight up with an initial velocity of 19.6 m/s. What time interval elapses between the rock's being thrown and its return to the original launch point? (Acceleration due to gravity is 9.80 m/s2.)
a. 4.00 scorrect
b. 5.00 s
c. 8.00 s
d. 10.0 s

44. Two objects of different mass are released simultaneously from the top of a 20-m tower and fall to the ground. If air resistance is negligible, which statement best applies?
a. The greater mass hits the ground first.
b. Both objects hit the ground together.correct
c. The smaller mass hits the ground first.
d. No conclusion can be made with the information given.

45. A baseball catcher throws a ball vertically upward and catches it in the same spot when it returns to his mitt. At what point in the ball's path does it experience zero velocity and non zero acceleration at the same time?
a. midway on the way up
b. at the top of its trajectorycorrect
c. the instant it leaves the catcher's hand
d. the instant before it arrives in the catcher's mitt

46. A baseball is released at rest from the top of the Washington Monument. It hits the ground after falling for 6.0 s. What was the height from which the ball was dropped? (g = 9.8 m/s2 and assume air resistance is negligible)
a. 1.5 x 102 m
b. 1.8 x 102 mcorrect
c. 1.1 x 102 m
d. 2.1 x 102 m

51. Human reaction time is usually about 0.20 s. If your lab partner holds a ruler between your finger and thumb and releases it without warning, how far can you expect the ruler to fall before you catch it? The nearest value is:
a. 4.0 cm.
b. 9.8 cm.
c. 16 cm.
d. 20 cm.correct

52. At the top of a cliff 100 m high, Raoul throws a rock upward with velocity 15.0 m/s. How much later should he drop a second rock from rest so both rocks arrive simultaneously at the bottom of the cliff?
a. 5.05 s
b. 3.76 s
c. 2.67 s
d. 1.78 scorrect

55. A basketball player can jump 1.6 m off the hardwood floor. With what upward velocity did he leave the floor?
a. 1.4 m/s
b. 2.8 m/s
c. 4.2 m/s
d. 5.6 m/scorrect

58. A ball is thrown vertically upwards at 19.6 m/s. For its complete trip (up and back down to the starting position), its average speed is:

a. 19.6 m/s.
b. 9.80 m/s.correct
c. 4.90 m/s.
d. zero

4. When we add a displacement vector to another displacement vector, the result is:
a. a velocity.
b. an acceleration.
c. another displacement.correct
d. a scalar.

5. A student adds two vectors with magnitudes of 200 and 40. Which one of the following is the only possible choice for the magnitude of the resultant?
a. 100
b. 200correct
c. 260
d. 40

7. The first displacement is 6 m and the second displacement is 3 m. They cannot add together to give a total displacement of:
a. 2 m.correct
b. 3 m.
c. 6 m.
d. 9 m.

8. Vector is 3 m long and vector is 4 m long. The length of the sum of the vectors must be:

a. 5 m.
b. 7 m.
c. 12 m.
d. some value from 1 m to 7 m.correct

15. In a 2 dimensional Cartesian coordinate system the x-component of a given vector is equal to that vector's magnitude multiplied by which trigonometric function, with respect to the angle between vector and x-axis?
a. sine
b. cosinecorrect
c. tangent
d. cotangent

16. In a 2 dimensional Cartesian coordinate system the y-component of a given vector is equal to that vector's magnitude multiplied by which trigonometric function, with respect to the angle between vector and y-axis?
a. sine
b. cosinecorrect
c. tangent
d. cotangent

29. A jogger runs halfway around a circular path with a radius of 60 m. What, respectively, are the magnitude of the displacement and the distance jogged?
a. 60 m, 188 m
b. 120 m, 188 mcorrect
c. 0 m, 377 m
d. 120 m, 377 m

30. A runner circles a track of radius 100 m in 100 s moving at a constant rate. If the runner was initially moving north, what has been the runner's average acceleration when halfway around the track?
a. At a constant rate, the average acceleration would be zero.
b. 2 m/s2, west
c. 0.25 m/s2, southcorrect
d. No answer is correct.

37. A helicopter is traveling at 40 m/s at a constant altitude of 100 m over a level field. If a wheel falls off the helicopter, with what speed will it hit the ground? (g = 9.8 m/s2 and air resistance negligible)
a. 40 m/s
b. 50 m/s
c. 60 m/scorrect
d. 70 m/s

38. A ball is rolled horizontally off a table with an initial speed of 0.24 m/s. A stopwatch measures the ball's trajectory time from table to the floor to be 0.30 s. What is the height of the table? (g = 9.8 m/s2 and air resistance is negligible)
a. 0.11 m
b. 0.22 m
c. 0.33 m
d. 0.44 mcorrect

39. A ball is rolled horizontally off a table with an initial speed of 0.24 m/s. A stop watch measures the ball's trajectory time from table to the floor to be 0.30 s. How far away from the table does the ball land? (g = 9.8 m/s2 and air resistance is negligible)
a. 0.055 m
b. 0.072 mcorrect
c. 1.2 m
d. 1.9 m

40. A stone is thrown at an angle of 30 above the horizontal from the top edge of a cliff with an initial speed of 12 m/s. A stop watch measures the stone's trajectory time from top of cliff to bottom to be 5.6 s. What is the height of the cliff? (g = 9.8 m/s2 and air resistance is negligible)
a. 58 m
b. 154 m
c. 120 mcorrect
d. 197 m

41. A stone is thrown at an angle of 30 above the horizontal from the top edge of a cliff with an initial speed of 12 m/s. A stop watch measures the stone's trajectory time from top of cliff to bottom to be 5.6 s. How far out from the cliff's edge does the stone travel horizontally? (g = 9.8 m/s2 and air resistance is negligible)
a. 58 mcorrect
b. 154 m
c. 120 m
d. 197 m

46. A bridge that was 5.0 m long has been washed out by the rain several days ago. How fast must a car be going to successfully jump the stream? Although the road is level on both sides of the bridge, the road on the far side is 2.0 m lower than the road on this side.
a. 5.0 m/s
b. 7.8 m/scorrect
c. 13 m/s
d. 25 m/s

54. A fireman, 50.0 m away from a burning building, directs a stream of water from a fire hose at an angle of 30.0 above the horizontal. If the initial speed of the stream is 40.0 m/s, at what height will the stream of water strike the building?
a. 9.60 m
b. 13.4 m
c. 18.7 mcorrect
d. 22.4 m

55. The highest mountain on Mars is Olympus Mons, rising 22 000 meters above the Martian surface. If we were to throw an object horizontally off the mountain top, how long would it take to reach the surface? (Ignore atmospheric drag forces and use gMars = 3.72 m/s2.)
a. 1.8 minutescorrect
b. 2.4 minutes
c. 3.0 minutes
d. 0.79 minute

59. A river flows due east at 3.0 m/s. A boat crosses the 300-m-wide river by maintaining a constant velocity of 10 m/s due north relative to the water. If no correction is made for the current, how far downstream does the boat move by the time it reaches the far shore?
a. 6 m
b. 30 m
c. 60 m
d. 90 mcorrect

60. A boat moves through the water in a river at a speed of 8 m/s relative to the water. The boat makes a trip downstream and then makes a return trip upstream to the original starting place. Which trip takes longer?
a. the downstream trip
b. the upstream tripcorrect
c. Both trips take the same amount of time.
d. The answer cannot be figured without knowing the speed of the river flow.

2. If we know an object is moving at constant velocity, we may assume:
a. the net force acting on the object is zero.correct
b. there are no forces acting on the object.
c. the object is accelerating.
d. the object is losing mass.

11. If we know that a nonzero net force is acting on an object, which of the following must we assume regarding the object's condition? The object is:
a. at rest.
b. moving with a constant velocity.
c. being accelerated.correct
d. losing mass.

4. What condition must apply to a system's state of motion for it to be regarded as an inertial frame of reference?
a. in decreasing velocity
b. in constant velocitycorrect
c. in constant acceleration
d. in increasing acceleration

5. A 7.0-kg bowling ball experiences a net force of 5.0 N. What will be its acceleration?
a. 35 m/s2
b. 7.0 m/s2
c. 5.0 m/s2
d. 0.71 m/s2correct

6. An astronaut applies a force of 500 N to an asteroid, and it accelerates at 7.00 m/s2. What is the asteroid's mass?
a. 71 kgcorrect
b. 135 kg
c. 441 kg
d. 3 500 kg

14. A cart of weight 20 N is accelerated across a level surface at 0.15 m/s2. What net force acts on the wagon? (g = 9.8 m/s2)
a. 0.92 N
b. 0.31 Ncorrect
c. 3.0 N
d. 4.5 N

15. A rock is rolled in the sand. It starts at 5.0 m/s, moves in a straight line for a distance of 3.0 m, and then stops. What is the magnitude of the average acceleration?
a. 1.8 m/s2
b. 4.2 m/s2correct
c. 5.4 m/s2
d. 6.2 m/s2

17. A 70.0 kg man jumps 1.00 m down onto a concrete walkway. His downward motion stops in 0.0200 seconds. If he forgets to bend his knees, what force is transmitted to his leg bones?
a. 15 500 Ncorrect
b. 7 010 N
c. 4 900 N
d. 3 500 N

26. Two blocks, joined by a string, have masses of 6.0 and 9.0 kg. They rest on a frictionless horizontal surface. A 2nd string, attached only to the 9-kg block, has horizontal force = 30 N applied to it. Both blocks accelerate. Find the tension in the string between the blocks.
a. 18 N
b. 28 N
c. 12 Ncorrect
d. 15 N

28. An airplane of mass 1.2 × 104 kg tows a glider of mass 0.6 × 104 kg. The airplane propellers provide a net forward thrust of 3.6 × 104 N. What is the glider's acceleration?
a. 2.0 m/s2correct
b. 3.0 m/s2
c. 6.0 m/s2
d. 9.8 m/s2

29. Two blocks of masses 20 kg and 8 kg are connected together by a light string and rest on a frictionless level surface. Attached to the 8-kg mass is another light string, which a person uses to pull both blocks horizontally. If the two-block system accelerates at 0.5 m/s2 what is the tension in the connecting string between the blocks?
a. 14 N
b. 6 N
c. 10 Ncorrect
d. 4.0 N

30. Two blocks of masses 20 kg and 8.0 kg are connected together by a light string and rest on a frictionless level surface. Attached to the 8-kg mass is a second light string, which a person uses to pull both blocks horizontally. If the two-block system accelerates at 0.5 m/s2, what is the tension in the second string attached to the 8-kg mass?
a. 14 Ncorrect
b. 6.0 N
c. 10 N
d. 4.0 N

32. A 15-kg block rests on a level frictionless surface and is attached by a light string to a 5.0-kg hanging mass where the string passes over a massless frictionless pulley. If g = 9.8 m/s2, what is the tension in the connecting string?
a. 65 N
b. 17 N
c. 49 N
d. 37 Ncorrect

33. An elevator weighing 20 000 N is supported by a steel cable. What is the tension in the cable when the elevator is being accelerated upward at a rate of 3.00 m/s2? (g = 9.80 m/s2)
a. 13 900 N
b. 23 100 N
c. 20 000 N
d. 26 100 Ncorrect

35. As I slide a box at constant speed up a frictionless slope, pulling parallel to the slope, the tension in the rope will be:
a. greater than the tension would be if the box were stationary.
b. greater than the weight of the box.
c. equal to the weight of the box.
d. less than the weight of the box.correct

36. A boxcar of mass 200 tons at rest becomes uncoupled on a 2.5 grade. If the track is considered to be frictionless, what speed does the boxcar have after 10 seconds?
a. 0.37 m/s
b. 0.59 m/s
c. 1.3 m/s
d. 4.3 m/scorrect

37. As a 3.0-kg bucket is being lowered into a 10-m-deep well, starting from the top, the tension in the rope is 9.8 N. The acceleration of the bucket will be:
a. 6.5 m/s2 downward.correct
b. 9.8 m/s2 downward.
c. zero.
d. 3.3 m/s2 upward.

44. A 500-N tightrope walker stands at the center of the rope such that each half of the rope makes an angle of 10.0 with the horizontal. What is the tension in the rope?
a. 1 440 Ncorrect
b. 1 000 N
c. 500 N
d. 2 900 N

45. A 500-N tightrope walker stands at the center of the rope. If the rope can withstand a tension of 1 800 N without breaking, what is the minimum angle the rope can make with the horizontal?
a. 4
b. 8correct
c. 10
d. 15

46. A 20 kg traffic light hangs midway on a cable between two poles 40 meters apart. If the sag in the cable is 0.40 meters, what is the tension in each side of the cable?
a. 12 000 N
b. 9 800 N
c. 4 900 Ncorrect
d. 980 N

53. A 100-kg box is placed on a ramp. As one end of the ramp is raised, the box begins to move downward just as the angle of inclination reaches 15 . What is the coefficient of static friction between box and ramp?
a. 0.15
b. 0.27correct
c. 0.77
d. 0.95

55. A 250-kg crate is placed on an adjustable inclined plane. If the crate slides down the incline with an acceleration of 0.70 m/s2 when the incline angle is 25 , then what should the incline angle be for the crate to slide down the plane at constant speed? (g = 9.8 m/s2)
a. 12
b. 21correct
c. 25
d. 29

57. It is late and Carlos is sliding down a rope from his third floor window to meet his friend Juan. As he slides down the rope faster and faster, he becomes frightened and grabs harder on the rope, increasing the tension in the rope. As soon as the upward tension in the rope becomes equal to his weight:
a. Carlos will stop.
b. Carlos will slow down.
c. Carlos will continue down at a constant velocity.correct
d. the rope must break.

60. As a car goes up a hill, there is a force of friction between the road and the tires rolling on the road. The maximum force of friction is equal to:
a. the weight of the car times the coefficient of kinetic friction.
b. the normal force of the road times the coefficient of kinetic friction.
c. the normal force of the road times the coefficient of static friction.correct
d. zero.

61. As a car moves forward on a level road at constant velocity, the net force acting on the tires is:
a. greater than the normal force times the coefficient of static friction.
b. equal to the normal force times the coefficient of static friction.
c. the normal force times the coefficient of kinetic friction.
d. zero.correct

64. Two objects, A and B, are placed on an inclined plane that can be rotated to different angles of elevation. A starts to slide at twice the angle of elevation that B starts sliding. The respective coefficients for static friction for A and B are A and B. Choose the last answer that is correct.
a. B > A
b. A > Bcorrect
c. B = 2 A
d. A = 2 B

68. A man pulls a sled at a constant velocity across a horizontal snow surface. If a force of 80 N is being applied to the sled rope at an angle of 53 to the ground, what is the force of friction between sled and snow?
a. 80 N
b. 64 N
c. 48 Ncorrect
d. 40 N

69. A trapeze artist, with swing, weighs 800 N; he is momentarily held to one side by his partner so that the swing ropes make an angle of 30.0 with the vertical. In such a condition of static equilibrium, what is the horizontal force being applied by the partner?
a. 924 N
b. 400 N
c. 196 N
d. 462 Ncorrect

70. A trapeze artist, with swing, weighs 800 N; he is being held to one side by his partner so that the swing ropes make an angle of 30.0 with the vertical. In such a condition of static equilibrium what is the tension in the rope?
a. 924 Ncorrect
b. 400 N
c. 196 N
d. 461 N

71. A 200-N crate rests on an ramp; the maximum angle just before it slips is 25 with the horizontal. What is the coefficient of static friction between crate and ramp surfaces?
a. 0.11
b. 0.21
c. 0.38
d. 0.47correct

72. A 150-N sled is pulled up a 28 slope at a constant speed by a force of 100 N. What is the coefficient of kinetic friction between sled and slope?
a. 0.53
b. 0.22correct
c. 0.13
d. 0.33

75. Hector drives a pickup truck horizontally at 15.0 m/s. He is transporting a crate of delicate lead crystal. If the coefficient of static friction between the crate and the truck bed is 0.400, what is the minimum stopping distance for the truck so the crate will not slide?
a. 28.7 mcorrect
b. 51.0 m
c. 33.6 m
d. 44.4 m

80. The coefficient of static friction between the tires of a car and the street is s = 0.77. Of the following, what is the steepest inclination angle of a street on which a car can be parked (with wheels locked) without slipping?
a. 22.5
b. 30
c. 37correct
d. 45

82. A 100-N block, on a 30 incline, is being held motionless by friction. The coefficient of static friction between the block and the plane is 0.60. The force due to friction is:
a. 0 N.
b. 30 N.
c. 50 N.correct
d. 52 N.

83. A block is launched up an incline plane. After going up the plane, it slides back down to its starting position. The coefficient of friction between the block and the plane is 0.3. The time for the trip up the plane:
a. is the same as the time for the trip down.
b. is more than the time for the trip down.
c. is less than the time for the trip down.correct
d. cannot be found compared without knowing the angle of inclination.

84. A block is launched up an incline plane. After going up the plane, it slides back down to its starting position. The coefficient of friction between the block and the plane is 0.3. The speed of the block when it reaches the starting position on the trip down:
a. is the same as the launching speed.
b. is less than the launching speed.correct
c. is more than the launching speed.
d. cannot be compared to the launch speed with the information given.