PHY1 Final Exam Review

84. A railroad freight car, mass 15,000kg, is allowed to coast along a level track at a speed of 2.0m/s. It collides with a 50,000kg second car, initially at rest and with breaks released. What is the speed of the two cars after coupling? A. 0.46m/s B. 0.60m/s C. 1.2m/s D. 1.8m/s

A. 0.46m/s

27. What is the difference between 103.5 and 102.24? A. 1.3 B. 1.26 C. 1.260 D. 1.2600

A. 1.3

21. A motorist travels 160km at 80km/h and 160km at 100km/h. What is the average speed of the motorist for this trip? A. 84km/h B. 89km/h C. 90km/h D. 91km/h

B. 89km/h

10. Suppose a ball is thrown straight up. Make a statement about the velocity and the acceleration when the ball reaches the highest point. A. Both its velocity and its acceleration are zero. B. Its velocity is zero and its acceleration is not zero. C. Its velocity is not zero and its acceleration is zero. D. Neither its velocity not its acceleration is zero.

B. Its velocity is zero and its acceleration is not zero.

8. Suppose that a car traveling to the East (+x direction) begins to slow down as it approaches a traffic light. Make a statement concerning its acceleration. A. The car is decelerating, and its acceleration is positive. B. The car is decelerating, and its acceleration is negative. C. The acceleration is zero. D. A statement cannot be made using the information given.

B. The car is decelerating, and its acceleration is negative.

77. When a cannon fires a cannonball, the cannon will recoil because the A. energy of the cannonball and cannon is conserved B. momentum of the cannonball and cannon is conserved C. energy of the cannon is greater than the energy of the cannonball D. momentum of the cannon is greater than the energy of the cannonball

B. momentum of the cannonball and cannon is conserved

81. In an elastic collision, if the momentum is conserved, then which of the following statements is true about kinetic energy? A. Kinetic energy is also conserved. B. Kinetic energy is gained. C. Kinetic energy is lost. D. None of the above.

C. Kinetic energy is lost.

1. Which student used the least precise scale? Student A: 49.06 Student B: 49 Student C: 50 Student D: 49.2

Student C

66. A 10kg mass hung onto a spring causes the spring to stretch 2.0cm. What is the spring constant? A. 5.0 x 10^2 N/m B. 4.9 x 10 ^3 N/m C. 20N/m D. 2.0N/m

B. 4.9 x 10^3 N/m

68. A force of 10N is applied horizontally to a 2.0kg mass on a level surface. The coefficient of kinetic friction between the mass and the surface is 0.20. If the mass is moved a distance of 7.5m, what is the change in its kinetic energy? A. 20J B. 39J C. 46J D. 61j

C. 46J

82. A handball of mass 0.10kg, traveling at 30m/s, strikes a wall and rebounds at 24m/s. What is the change in the momentum of the ball? A. 0.60kg*m/s B. 1.2kg*m/s C. 5.4kg*m/s D. 72kg*m/s

C. 5.4kg*m/s

18. A cart with an initial velocity of 5.0m/s experiences a constant acceleration of 2.0m/s^2. What is the cart's displacement during the first 6.0s of its motion? A. 10m B. 55m C. 66m D. 80m

C. 66m

16. What must be your average speed in order to travel 350km in 5.15h? A. 66.0km/h B. 67.0km/h C. 68.0km/h D. 69.0km/h

C. 68.0km/h

93. The second hand of a clock has a length of 0.30m. What distance does the tip of the second hand sweep through in 3 minutes and 45 seconds? A. 1.1m B. 1.8m C. 7.1m D. 13m

C. 7.1m

14. The area under a curve in a velocity versus time graph gives: A. acceleration B. velocity C. displacement D. position

C. displacement

3. The number of significant figures in 10001 is: A. two B. three C. five D. six

C. five

43. A block of mass M slides down a frictionless plane inclined at an angle theta with the horizontal. The normal reaction force exerted by the place on the block is A. mg B. mg sin(theta) C. mg cos(theta) D. zero, since the plane is frictionless

C. mg cos(theta)

71. If you push twice as hard against a stationary brick wall, the amount of work you do A. doubles B. is cut in half C. remains constant at zero D. remains constant but non-zero

C. remains constant at zero

58. The quantity Fd/t is A. the kinetic energy of the object B. the potential energy of the object C. the power supplied to the object by the force D. the work done on the object by the force

C. the power supplied to the object by the force

63. A car goes around a curve with a radius (r) at a constant speed (v). What is the direction of the net force on the car? A. toward the front of the car B. away from the curve's center C. toward the curve's center D. toward the back of the car

C. toward the curve's center

55. The area under the curve on a force versus position (F vs. x) graph for a spring represents A. power B. kinetic energy C. work D. gravitational potential energy

C. work

31. A vector has magnitude 8.0m at an angle of 30 degrees below the +x-axis. The y component is A. 6.9m B. -6.9m C. 4.0m D. -4.0m

D. -4.0m

47. An object slides on a level surface in the +x direction. It slows and comes to a stop with a constant acceleration of -2.4m/s^2. What is the coefficient of kinetic friction between the object and the floor? A. impossible to determine without knowing the mass of the object B. 0.50 C. 4.9 D. 0.25

D. 0.25

90. A 0.060kg tennis ball initially moving at a speed of 12m/s is struck by a racket causing it to rebound in the opposite direction at a speed of 18m/s. What is the change in momentum of the ball? A. 0.36kg*m/s B. 0.72kg*m/s C. 1.1kg*m/s D. 1.8kg*m.s

D. 1.8kg*m/s

99. A wheel accelerates with a constant angular acceleration of 4.5rad/s^2. If the initial angular velocity is 1.0rad/s, what is the angular velocity at t = 2.0s? A. 1.0rad/s B. 7.0rad/s C. 9.0rad/s D. 10rad/s

D. 10rad/s

28. The resultant of two vectors is the smallest when the angle between them is A. 0 B. 45 C. 90 D. 180

D. 180

100. How many radians does a 0.300m radius automobile tire rotate after starting from rest and accelerating at a constant angular acceleration of 2.00rad/s^2 over a 5.00s interval? A. 1.00rad B. 2.00rad C. 12.5rad D. 25.0rad

D. 25.0rad

96. A boy and a girl are balanced on a massless seesaw. The boy has a mass of 75kg and the girl's mass if 50kg. If the boy sits 2.0m from the pivot point on one side of the seesaw, where must the girl sit on the other side? A. 1.3m B. 2.3m C. 2.5m D. 3.0m

D. 3.0m

17. If you are driving 72km/h along a straight road and you look to the side for 4.0s, how far do you travel during this inattentive period? A. 18m B. 20m C. 40m D. 80m

D. 80m

11. A ball is thrown straight up, reaches a max height, then falls to its initial height. Make a statement about the direction of the velocity and acceleration as the ball is coming down. A. Both its velocity and its acceleration point upward. B. Its velocity points upward and its acceleration points downward. C. Its velocity points downward and its acceleration points upward. D. Both its velocity and its acceleration point downward.

D. Both its velocity and its acceleration point downward.

41. A 20N weight and a 5.0N weight are dropped simultaneously from the same height. Ignore air resistance. Compare their accelerations. A. They both accelerate at the same rate because the earth pulls them with the same force. B. The 20N weight accelerates faster because it has more inertia. C. The 5.0N weight accelerates faster because it has a smaller mass. D. They both accelerate at the same rate because they have the same weight to mass ratio.

D. They both accelerate at the same rate because they have the same weight to mass ratio.

37. If you can exert a force F on an object, the force which the object exerts on you will A. depend on whether or not the object is moving B. depend on whether or not you are moving C. depend on the relative masses of you and the object D. always be F

D. always be F

40. A stone is thrown straight up. At the top of its path, the net force acting on it is A. greater than its weight B. greater than zero, but less than its weight C. instantaneously equal to zero D. equal to its weight

D. equal to its weight

83. A 70kg astronaut is space-walking outside the space capsule and is stationary when the tether line breaks. As a means of returning to the capsule, he throws a 2.0kg space hammer at a speed of 14m/s away from the capsule. At what speed does the astronaut move toward the capsule? A. 0.40m/s B. 1.5m/s C. 3.5m/s D. 5.0m/s

A. 0.4m/s

46. A 6kg object is on a frictionless inclined plane. The plane is inclined at an angle of 30 degrees with the horizontal. What is the object's acceleration? A. 0.50 g B. 0.56 g C. 0.87 g D. 1.0 g Now assume that object above has an acceleration of 2m/s^2 down the plane because of friction slowing it down. What is the force of friction? A. 2.9N B. 8.7N C. 17.4N D. 23.6N What is the coefficient of friction between the above object and the inclined track? A. 0.68 B. 0.26 C. 1.36 D. 0.34

A. 0.50 g C. 17.4N D. 0.34

86. A 10.0g bullet moving at 300m/s is fired into a 1.00kg block at rest. The bullet emerges with half of its original speed. What is the velocity of the block right after the collision? A. 1.50m/s B. 2.97m/s C. 3.00m/s D. 273m/s

A. 1.50m/s

5. 0.0001776 can also be expressed as: A. 1.776 x 10^ -4 B. 17.72 x 10^ 4 C. 1772 x 10^ 5 D. 177.2 x 10^ 7

A. 1.776 x 10^ -4

29. A ball is thrown with a velocity of 20m/s at an angle of 60 degrees above the horizontal. What is the horizontal component of its instantaneous velocity at the exact top of its trajectory? A. 10m/s B. 17ms C. 20m/s D. zero

A. 10m/s

59. The acceleration of gravity on the Moon is one-sixth what it is on Earth. An object of mass 12kg is taken to the Moon. What is the mass there? A. 12kg B. 72kg C. 72N D. 12N

A. 12kg

45. An elevator weighing 2000N is moving downward with constant velocity. What is the tension in the cable? A. 2000N B. greater than 2000N C. less than 2000N D. impossible to known with the information given The above elevator goes from 1m/s upward to 3m/s upward in a time of 1s. During this time, what is the tension in the cable? A. 400N B. 1600N C. 2000N D. 2400N A person of weight 480N stands on a scale in the elevator. What will the scale be reading when the elevator is accelerating downward at 4.00m/s^2? A. 196N B. 284N C. 676N D. 480N A person of weight 480N stands on a kg scale in the elevator. What mass will the scale be reading when the elevator is accelerating downward at 4.00m/s^2? A. 30kg B. 20kg C. 69kg D. 49kg

A. 2000N D. 2400N B. 284N A. 30kg

85. A constant 9.0N net force acts for 3.0m on a 6.0kg object. What is the object's change of velocity? A. 3.0m/s B. 9.0m/s C. 27m/s D. 110m/s

A. 3.0m/s

98. The bolts on a car wheel require tightening to a torque of 90N*m. If a 30cm long wrench is used, what is the magnitude of the force required when the force is perpendicular to the wrench? A. 300N B. 150N C. 30N D. 15N

A. 300N

54. Does the centripetal force acting on an object do work on the object? A. No, because the force and the displacement of the object are perpendicular B. Yes, since it takes energy to turn an object C. No, because the object has constant speed D. Yes, since a force acts and the object moves, and work is force times distance

A. No, because the force and the displacement of the object are perpendicular

42. A packing crate slides down an inclined ramp at constant velocity. Thus we can deduce that A. a frictional force is acting on it B. a net downward force is acting on it C. it may be accelerating D. it is not acted on by appreciable gravitational force

A. a frictional force is acting on it

35. A constant net force acts on an object. Describe the motion of the object. A. constant acceleration B. constant speed C. constant velocity D. increasing acceleration

A. constant acceleration

12. Ball A is dropped from the top of a building. One second later, ball B is dropped from the same building. As time progresses, the distance between them: A. increases B. remains constant C. decreases D. cannot be determined from the information given

A. increases

80. Two objects collide and bounce off each other. Linear momentum A. is definitely conserved B. is definitely not conserved C. is conserved only if the collision is elastic

A. is definitely conserved

2. The metric prefix for one-thousandth is: A. milli B. centi C. kilo D. mega

A. milli

78. A rubber ball and a lump of putty have equal mass. They are thrown with equal speed against a wall. The ball bounces back with nearly the same speed with which it hit. The putty sticks to the wall. Which object experiences the greater momentum change? A. the ball B. the putty C. both experience the same momentum change D. cannot be determined from the information given

A. the ball

56. The gravitational force between two objects is proportional to A. the product of the two objects B. the square of the distance between the two objects C. the distance between the two objects D. the square of the product of the two objects

A. the product of the two objects

51. Consider a small satellite moving in a circular orbit (radius r) about a spherical planet (mass M). Which expression gives this satellite's orbital velocity? A. v = GM/r B. GM/r^2 C. (GM/r)^1/2 D. (GM/r^2)^1/2

A. v = GM/r

34. You are standing in a moving bus, facing forward, and you suddenly fall forward. You can imply from this that the bus's A. velocity decreased B. velocity increased C. speed remained the same, but its turning to the right D. speed remained the same, but its turning to the left

A. velocity decreased

88. A ping-pong ball moving east at a speed of 4m/s collides with a stationary bowling ball. The ping-pong ball bounces back to the west, and the bowling ball moves very slowly to the east. Which object experiences the greater magnitude impulse during the collision? A. Neither; both experienced the same magnitude impulse B. the ping-pong ball C. the bowling ball D. It's impossible to tell since the velocities after the collision are unknown

A.Neither; both experiences the same magnitude impulse

76. A roller coaster car (mass = M) is on a track that forms a circular loop (radius = r) in the vertical plane. If the car is to just maintain contact with the track at the top of the loop, what is the minimum value for its speed at that point? A. rg B. (rg)^1/2 C. (2rg)^1/2 D. (0.5rg)^1/2

B. (rg)^1/2

26. What is the conversion factor between cm^2 and m^2? A. 0.01m^2/cm^2 B. 0.0001m^2/cm^2 C. 100m^2/cm^2 D. 10000m^2/cm^2

B. 0.0001m^2/cm^2

60. An object moves with a constant speed of 5m/s on a circular track of radius 150m. What is the acceleration of the object? A. zero B. 0.17m/s^2 C. 5.0m/s^2 D. 6.0m/s^2

B. 0.17m/s^2

25. What is the conversion factor between km/h and m/s? A. 0.0278m/s B. 0.278m/s C. 3.60m/s D. 16.7m/s

B. 0.278m/s

67. A spring is characterized by a spring constant of 60N/m. How much potential energy does it store when stretched by 10cm? A. 3.0 x 10^-3 J B. 0.30J C. 60J D. 600J

B. 0.30J

48. A 4kg object has an acceleration of 3m/s^2 down an inclined plane. The plane is inclined at an angle of 40 degrees with the horizontal. What is the coefficient of friction? A. 0.22 B. 0.44 C. 0.34 D. 0.66

B. 0.44

4. The length and width of a rectangle are 1.125m and 0.606m, respectively. Multiplying, your calculator gives the product as 0.68175. Rounding properly to the correct number of significant figures, the area should be written as: A. 0.68m^2 B. 0.682m^2 C. 0.6818m^2 D. 0.68175m^2

B. 0.682m2

50. How many revolutions per minute must a circular, rotating space station of radium 1000m rotate to produce an artificial gravity of 9.80m/s^2? A. 0.65rpm B. 0.95rpm C. 0.85rpm D. 0.75rpm

B. 0.95rpm

65. A car is negotiating a flat curve of radius 50m with a speed of 20m/s. The centripetal force provided by friction is 0.8 x 10^4 N. What is the mass of the car? A. 500kg B. 1000kg C. 1500kg D. 2000kg

B. 1000kg

24. Express the number 0.02 days using a prefix. A. 2 decidays B. 2 centidays C. 2 millidays D. 2 microdays

B. 2 centidays

97. How many rad/s is 25 revolutions per minute equivalent to? A. 0.42rad/s B. 2.6rad/s C. 160rad/s D. 240rad/s

B. 2.6rad/s

44. A sports car of mass 1000kg can accelerate from rest to 27m/s in 7.0s. What is the average forward force on the car? A. 2.6 x 10^2N B. 3.9 x 10^3N C. 2.7 x 10^4N D. 1.9 x 10^5N

B. 3.9 x 10^3N

87. A 1500kg car traveling at 90.0km/h east collides with a 3000kg car traveling at 60.0km/h south. The two cars stick together after the collision. What is the speed of the cars after the collision? A. 30km/h B. 50km/h C. 63km/h D. 70km/h What is the direction of motion of the cars after collision? A. 36.9degrees S of E B. 36.9degrees W of S C. 53.1degrees S of E D. 53.1degrees W of S

B. 50km/h C. 53.1degrees S of E

22. A ball is thrown straight up with a speed of 36.0m/s. How long does it take to return to its starting point? A. 3.67s B. 7.35s C. 11.0s D. 14.7s

B. 7.35s

75. A 6kg mass is moving with a speed of 5.0m/s. How much work is required to stop the mass? A. 50J B. 75J C. 100J D. 125J

B. 75J

69. Satellite A has twice the mass of Satellite B and rotates in the same orbit. Compare the two satellite's speeds. A. The speed of B is twice the speed of A. B. The speed of B is equal to the speed of A. C. The speed of B is one-fourth the speed of A. D. The speed of B is half the speed of A.

B. The speed of B is equal to the speed of A.

39. A golf club hits a golf club with a force of 2400N. The golf ball hits the club with a force of A. slightly less than 2400N B. exactly 2400N C. slightly more than 2400N D. close to 0N

B. exactly 2400N

13. Ball A is dropped from the top of a building. One second later, ball B is dropped from the same building. As time progresses, the difference in their speeds: A. increases B. remains constant C. decreases D. cannot be determined from the information given

B. remains constant

23. Ignoring air resistance, the horizontal component of a projectile's velocity A. is zero B. remains constant C. continuously increases D. continuously decreases

B. remains constant

91. A boy and a girl are riding a merry-go-round which is turning at a constant rate. The boy is near the outer edge, while the girl is closer to the center. Who has the greater centripetal acceleration? A. the girl B. the boy C. both have the same non-zero centripetal acceleration D. both have zero centripetal acceleration

B. the boy

92. Two equal forces are applied to a door. The first force is applied at the midpoint; the second force is applied at the doorknob. Both forces are applied perpendicular to the door. Which force exerts the greater torque? A. the first at the midpoint B. the second at the doorknob C. both exert equal non-zero torques D. both exert zero torque

B. the second at the doorknob

30. A stone is thrown horizontally from the top of a tower at the same instant a ball is dropped vertically. Which object is traveling faster when it hits the level ground below? A. it is impossible to tell from the information given B. the stone C. the ball D. neither, since both are traveling at the same speed

B. the stone

72. A 50N object was lifted 2.0m vertically and is being held there. How much work is being done in holding the box in this position? A. more than 100J B. zero C. less than 100J, but more than zero D. 100J

B. zero

61. A 30N box is pulled 7.6m up a 37 degree inclined plane. What is the work done by the weight (gravitational force) of the box? A. -11J B. -1.1 x 10^2 J C. -1.4 x 10^2 J D. -1.8 x 10^2 J

C. -1.4 x 10^2 J

6. How many grams is forty milligrams? A. 0.000040g B. 0.00040g C. 0.040g D. 40000g

C. 0.040g

33. A jumper in the long-jump goes into the jump with a speed of 12m/s at an angle of 20 degrees above the horizontal. How long is the jumper in the air before returning to the Earth? A. 0.21s B. 0.42s C. 0.84s D. 1.3s How high does the jumper jump? A. 0.21m B. 7.3m C. 0.86m D. 1.7m How far does the jumper jump? A. 3.4m B. 6.2m C. 9.4m D. 15m

C. 0.84s C. 0.86m C. 9.4m

70. At what rate is a 60.0kg boy using energy when he runs up a flight of stairs 10.0m high in 5.00s? A. 75.0W B. 735W C. 1.18kW D. 48W

C. 1.18kW

95. Assuming the lower arm has a mass of 2.8kg and its CM is 12cm from the elbow joint pivot, how much force must the extensor muscle in the upper arm exert on the lower arm to hold a 7.5kg shot put? The shot put is 30.0cm from the elbow joint. The muscle is 2.5cm from the elbow joint. A. 100N B. 500N C. 1000N D. 1500N

C. 1000N

19. A car goes from 40m/s to 80m/s in a distance of 200m. What is its average acceleration? A. 8.0m/s^2 B. 9.6m/s^2 C. 12m/s^2 D. 24m/s^2

C. 12m/s^2

94. A lever is 5.0m long and the fulcrum is at the 1.0m position. A weight is placed at the end of the lever that is closest to the fulcrum. If a worker pushes on the opposite end with 400N, what is the maximum weight that can be lifted? A. 80N B. 100N C. 1600N D. 2000N

C. 1600N

62. A 0.50kg mass is attached to the end of 0.5m string. The system is whirled in a horizontal circular path. If the max tension that the string can withstand is 350N, what is the max speed of the mass if the string is not to break? A. 700m/s B. 26m/s C. 19m/s D. 13m/s

C. 19m/s

32. A girl throws a rock horizontally, with a velocity of 10m/s, from a bridge. It falls a vertical distance of 20m to the water below. How far does the rock travel horizontally before striking the water? A. 14m B. 16m C. 20m D. 24m

C. 20m

9. Suppose a can, after an initial kick, moves up along a smooth hill of ice (no friction). Make a statement concerning its acceleration. A. It will travel at constant velocity with zero acceleration. B. It will have a constant acceleration up the hill, but a different constant acceleration when it comes back down the hill. C. It will have the same acceleration, both up the hill and down the hill. D. It will have a varying acceleration along the hill.

C. It will have the same acceleration, both up the hill and down the hill.

74. You slam on the brakes of your car in a panic and skid a certain distance on a straight, level road. If you had been traveling twice as fast, what distance would the car have skidded under the same conditions? A. It would have skidded 1.4 times farther. B. It would have skidded twice as far. C. It would have skidded 4 times farther. D. It is impossible to tell from the information given.

C. It would have skidded 4 times farther.

64. Can work be done on a system if there is no motion? A. Yes, if an outside force is provided B. Yes, since motion is only relative C. No, because of the way work is defined D. No, since a system which is not moving has no energy

C. No, because of the way work is defined

7. Suppose that an object travels from one point in space to another. Make a comparison between the displacement and the distance traveled. A. The displacement is either greater than or equal to the distance traveled. B. The displacement is always equal to the distance traveled. C. The displacement is either less than or equal to the distance traveled. D. The displacement can be either greater than, smaller than, or equal to the distance traveled.

C. The displacement is either less than or equal to the distance traveled.

79. A small car meshes with a large truck in a head-on collision. Which of the following statements concerning the magnitude of the average collisions force is correct? A. The truck experiences the greater average force. B. The small car experiences the greater average force. C. The small car and truck experience the same average force. D. It is impossible to tell since the masses and velocities are not given.

C. The small car and truck experience the same average force.

89. A 3.0kg object moves to the right at 4.0m/s. It collides head-on with a 6.0kg object moving to the left at 2.0m/s. Which statement is correct? A. The total momentum both before and after the collision is 24kg*m/s. B. The total momentum before the collision is 24kg*m/s, and after the collision is 0kg*m/s. C. The total momentum before and after the collision is zero. D. None of the above are true.

C. The total momentum before and after the collision is zero.

73. A truck weighs twice as much as a car, and is moving at twice the speed of the car. Which statement is true about the truck's kinetic energy compared to that of the car? A. All that can be said is that the truck has more kinetic energy. B. The truck has twice the kinetic energy of the car. C. The truck has eight times the kinetic energy of the car. D. The truck has four times the kinetic energy of the car.

C. The truck has eight times the kinetic energy of the car.

15. The slope of a velocity versus time graph gives: A. position B. velocity C. acceleration D. displacement

C. acceleration

53. When an object experiences uniform circular motion, the direction of the acceleration is A. in the same direction as the velocity vector B. in the opposite direction of the velocity vector C. is directed away from the center of the circular path D. is directed toward the center of the circular path

D. is directed toward the center of the circular path

36. The acceleration of an object is inversely proportional to A. the net force acting on it B. its position C. its velocity D. its mass

D. its mass

52. A pilot executes a vertical dive then follow a semi-circular arc until it is going straight up. Just as the plane is at its lowest point, the force on him is A. less than mg, and pointing up B. less than mg, and pointing down C. more than mg, and pointing down D. more than mg, and pointing up

D. more than mg, and pointing up

57. Two objects attract each other gravitationally. If the distance between their centers is doubled, the gravitational force A. is cut to one fourth B. is cut in half C. doubles D. quadruples

D. quadruples

38. A child's toy is suspended from the ceiling by means of a string. The weight of the toy is 8.0N. If this weight is the "action force," what is the "reaction force" according to Newton's third law? A. the string pulling upward on the toy with an 8.0N force B. the ceiling pulling upward on the string with an 8.0N force C. the string pulling downward on the ceiling with an 8.0N force D. the toy pulling upward on the Earth with an 8.0N force

D. the toy pulling upward on the Earth with an 8.0N force

20. If you run a complete loop around an outdoor track (400m) in 100s, your average velocity it A. 0.25m/s B. 1.0m/s C. 40,000m/s D. zero

D. zero

49. Student A has a mass of 75kg and student B has a mass of 57kg. They sit in identical office chairs facing each other. Student A places his feet on the knees of student B. Student A then suddenly pushes outward with his feet, causing both chairs to move. During the push, and while the students are still touching each other, A. neither student exerts a force on the other B. student A exerts a force on student B, but B does not exert a force on A C. each student exerts a force on the other, but B exerts a larger force D. each student exerts a force on the other, but A exerts a larger force E. each student exerts the same amount of force on the other

E. each student exerts the same amount of force on the other