PHYS 244 Final Exam Review

40) A bucket is being lowered by a very light rope with a constant downward velocity. The tension in the rope must be A) equal to the weight of the bucket. B) greater than the weight of the bucket. C) less than the weight of the bucket

A

52) As shown in the figure, a woman is straining to lift a large crate, but without success because it is too heavy. We denote the forces on the crate as follows: P is the magnitude of the upward force being exerted on the crate by the person, C is the magnitude of the vertical contact force on the crate by the floor, and W is the weight of the crate. How are the magnitudes of these forces related while the person is trying unsuccessfully to lift the crate? PICTURE A) P + C = W B) P + C < W C) P + C > W D) P = C

A

10) A racing car accelerates uniformly from rest along a straight track. This track has markers spaced at equal distances along it from the start, as shown in the figure. The car reaches a speed of 140 km/h as it passes marker 2. Where on the track was the car when it was traveling at half this speed, that is at 70 km/h? PICTURE A) Before marker 1 B) At marker 1 C) Between marker 1 and marker 2

A

14) Two objects are dropped from a bridge, an interval of 1.0 s apart. Air resistance is negligible. During the time that both objects continue to fall, their separation A) increases. B) decreases. C) stays constant. D) increases at first, but then stays constant. E) decreases at first, but then stays constant.

A

22) If the velocity versus time graph of an object is a horizontal line, the object is A) moving with zero acceleration. B) moving with constant non-zero acceleration. C) at rest. D) moving with increasing speed

A

26) For general projectile motion with no air resistance, the horizontal component of a projectile's acceleration A) is always zero. B) remains a non-zero constant. C) continuously increases. D) continuously decreases. E) first decreases and then increases.

A

3) Suppose that a car traveling to the west begins to slow down as it approaches a traffic light. Which of the following statements about its acceleration is correct? A) The acceleration is toward the east. B) Since the car is slowing down, its acceleration must be negative. C) The acceleration is zero. D) The acceleration is toward the west.

A

38) An elevator suspended by a vertical cable is moving downward but slowing down. The tension in the cable must be A) greater than the weight of the elevator. B) less than the weight of the elevator. C) equal to the weight of the elevator.

A

58) When a car goes around a banked circular curve at the proper speed speed for the banking angle, what force cause it to follow the circular path? A) the normal force from the road B) the friction force from the road C) gravity D) No force causes the car to do this because the car is traveling at constant speed and therefore has no acceleration.

A

61) If you stood on a planet having a mass four times that of Earth's mass, and a radius two times that of Earth's radius, you would weigh A) the same as you do on Earth. B) two times more than you do on Earth. C) two times less than you do on Earth. D) four times more than you do on Earth.

A

63) Which one has larger kinetic energy: a 500-kg object moving at 40 m/s or a 1000-kg object moving at 20 m/s? A) The 500-kg object B) The 1000-kg object C) Both have the same kinetic energy.

A

64) 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 4 times farther. B) It would have skidded twice as far. C) It would have skidded 1.4 times farther. D) It would have skidded one half as far. E) It is impossible to tell from the information given

A

7) Suppose that a car traveling to the west (-x direction) begins to slow down as it approaches a traffic light. Which statement concerning its acceleration must be correct? A) Its acceleration is positive. B) Its acceleration is negative. C) Its acceleration is zero. D) Its acceleration is decreasing in magnitude as the car slows down.

A

25) For general projectile motion with no air resistance, the horizontal component of a projectile's velocity A) remains zero. B) remains a non-zero constant. C) continuously increases. D) continuously decreases. E) first decreases and then increases.

B

27) For general projectile motion with no air resistance, the vertical component of a projectile's acceleration A) is always zero. B) remains a non-zero constant. C) continuously increases. D) continuously decreases. E) first decreases and then increases.

B

70) A heavy stone and a light stone are released from rest in such away that they both have the same amount of gravitational potential energy just as they are released. Air resistance is 16 negligibly small. Which of the following statements about these stones are correct? (There could be more than one correct choice.) A) The initial height of the light stone is greater than the initial height of the heavy stone. B) The stones must have been released from the same height. C) The stones both have the same speed just as they reach the ground. D) Just as it reaches the ground, the light stone is traveling faster than the heavy stone. E) The stones both have the same kinetic energy just as they reach the ground.

A,D,E

47) When a 45-kg person steps on a scale in an elevator, the scale reads a steady 480 N. Which of the following statements must be true? (There could be more than one correct choice.) A) The elevator is accelerating upward at a constant rate. B) The elevator is accelerating downward at a constant rate. C) The elevator is moving upward at a constant rate. D) The elevator is moving downward at a constant rate. E) From the given information, we cannot tell if the elevator is moving up or down.

A,E

11) When a ball is thrown straight up with no air resistance, the acceleration at its highest point A) is upward B) is downward 3 C) is zero D) reverses from upward to downward E) reverses from downward to upward

B

13) A ball is thrown straight up, reaches a maximum height, then falls to its initial height. Which of the following statements about the direction of the velocity and acceleration of the ball as it is going up is correct? 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 points downward.

B

19) The slope of a position versus time graph gives A) the distance traveled. B) velocity. C) acceleration. D) displacement.

B

23) If the velocity versus time graph of an object is a straight line making an angle of +30° (counter clockwise) with the time axis, the object is A) moving with constant non-zero speed. B) moving with constant non-zero acceleration. C) at rest. D) moving with increasing acceleration.

B

31) A pilot drops a package from a plane flying horizontally at a constant speed. Neglecting air resistance, when the package hits the ground the horizontal location of the plane will A) be behind the package. B) be directly over the package. C) be in front of the package. D) depend on the speed of the plane when the package was released.

B

32) James and John dive from an overhang into the lake below. James simply drops straight down from the edge. John takes a running start and jumps with an initial horizontal velocity of 25 m/s. If there is no air resistance, when they reach the lake below A) the splashdown speed of James is larger than that of John. B) the splashdown speed of John is larger than that of James. C) they will both have the same splashdown speed. D) the splashdown speed of James must be 9.8 m/s larger than that of John E) the splashdown speed of John must be 25 m/s larger than that of James.

B

36) You are in a train traveling on a horizontal track and notice that a piece of luggage starts to slide directly toward the front of the train. From this observation, you can conclude that this train is A) speeding up. B) slowing down. C) changing direction. D) speeding up and changing direction. E) slowing down and changing direction.

B

43) A horse pulls a cart with force F. As a result of this force the cart accelerates with constant acceleration. The magnitude of the force that the cart exerts on the horse A) is zero newtons. B) equal to the magnitude of F. C) less than the magnitude of F. D) greater than the magnitude of F. E) cannot be determined without knowing the mass of the horse.

B

46) The acceleration due to gravity is lower on the Moon than on Earth. Which one of the following statements is true about the mass and weight of an astronaut on the Moon's surface, compared to Earth? A) Mass is less, weight is the same. B) Mass is the same, weight is less. C) Both mass and weight are less. D) Both mass and weight are the same

B

51) Two blocks, A and B, are being pulled to the right along a horizontal surface by a horizontal 100-N pull, as shown in the figure. Both of them are moving together at a constant velocity of 2.0 m/s to the right, and both weigh the same. PICTURE Which of the figures below shows a correct free-body diagram of the horizontal forces acting on the lower block, B?

B

55) When a car goes around a circular curve on a horizontal road at constant speed, what force causes it to follow the circular path? A) the normal force from the road B) the friction force from the road C) gravity D) No force causes the car to do this because the car is traveling at constant speed and therefore has no acceleration.

B

6) Suppose that a car traveling to the east (+x direction) begins to slow down as it approaches a traffic light. Which statement concerning its acceleration must be correct? A) Its acceleration is in the +x direction. B) Its acceleration is in the -x direction. C) Its acceleration is zero. D) Its acceleration is decreasing in magnitude as the car slows down.

B

73) A very elastic rubber ball is dropped from a certain height and hits the floor with a downward speed v. Since it is so elastic, the ball bounces back with the same speed v going upward. Which of the following statements about the bounce are correct? (There could be more than one correct choice.) A) The ball had the same momentum just before and just after the bounce. B) The magnitude of the ball's momentum was the same just before and just after the bounce. C) The ball's momentum was conserved during the bounce. D) None of the above statements are correct.

B

9) Under what condition is average velocity equal to the average of the object's initial and final velocity? A) This can only occur if there is no acceleration. B) The acceleration is constant. C) This can occur only when the velocity is zero. D) The acceleration must be constantly increasing. E) The acceleration must be constantly decreasing.

B

1) Suppose that an object travels from one point in space to another. Make a comparison between the magnitude of the displacement and the distance traveled by this object. 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

12) Suppose a ball is thrown straight up and experiences no appreciable air resistance. What is its acceleration just before it reaches its highest point? A) zero B) slightly less than g C) exactly g D) slightly greater than g

C

15) Two objects are thrown from the top of a tall building. One is thrown up, and the other is thrown down, both with the same initial speed. What are their speeds when they hit the street? Neglect air resistance. A) The one thrown up is traveling faster. B) The one thrown down is traveling faster. C) They are traveling at the same speed. D) It is impossible to tell because the height of the building is not given.

C

16) Brick A is dropped from the top of a building. Brick B is thrown straight down from the same building, and neither one experiences appreciable air resistance. Which statement about their accelerations is correct? A) The acceleration of A is greater than the acceleration of B. B) The acceleration of B is greater than the acceleration of A. C) The two bricks have exactly the same acceleration. D) Neither brick has any acceleration once it is released.

C

17) An object is moving with constant non-zero velocity in the +x direction. The position versus time graph of this object is A) a horizontal straight line. B) a vertical straight line. C) a straight line making an angle with the time axis. D) a parabolic curve.

C

18) An object is moving with constant non-zero acceleration in the +x direction. The velocity versus time graph of this object is A) a horizontal straight line. B) a vertical straight line. C) a straight line making an angle with the time axis. D) a parabolic curve.

C

2) When is the average velocity of an object equal to the instantaneous velocity? A) only when the velocity is increasing at a constant rate B) only when the velocity is decreasing at a constant rate C) when the velocity is constant D) always E) never

C

20) The slope of a velocity versus time graph gives A) the distance traveled. B) velocity. C) acceleration. D) displacement

C

21) If the position versus time graph of an object is a horizontal line, the object is A) moving with constant non-zero speed. B) moving with constant non-zero acceleration. C) at rest. D) moving with increasing speed.

C

29) A ball is thrown horizontally from the top of a tower at the same instant that a stone is dropped vertically. Which object is traveling faster when it hits the level ground below if neither of them experiences any air resistance? A) It is impossible to tell because we do not know their masses. B) the stone C) the ball D) Both are traveling at the same speed

C

30) In an air-free chamber, a pebble is thrown horizontally, and at the same instant a second pebble is dropped from the same height. Compare the times of fall of the two pebbles. A) The thrown pebble hits first. B) The dropped pebble hits first. C) They hit at the same time. D) We cannot tell without knowing which pebble is heavier.

C

34) If you pound a feather with a hammer, which one feels a greater force? A) always the feather B) always the hammer C) The size of the force is always the same on both. D) If the feather moves, then it felt the greater force. Otherwise the force was the same on both.

C

35) A satellite is in orbit around the earth. Which one feels the greater force? A) the satellite because the earth is so much more massive B) the earth because the satellite has so little mass C) Earth and the satellite feel exactly the same force. D) It depends on the distance of the satellite from Earth

C

4) An auto manufacturer advertises that their car can go "from zero to sixty in eight seconds." This is a description of what characteristic of the car's motion? A) average speed B) instantaneous speed C) average acceleration D) instantaneous acceleration E) displacement

C

42) The figure shows two boxes, with m1 > m2, that are on a level frictionless surface. We can apply a horizontal force F either toward the right on m1 or toward the left on m2. The magnitude of the force that the boxes exert on each other is PICTURE A) zero newtons in either case. B) larger if F is applied toward the right. C) larger if F is applied toward the left. D) the same in either case.

C

54) You are making a circular turn in your car on a horizontal road when you hit a big patch of ice, causing the force of friction between the tires and the road to become zero. While the car is on the ice, it A) moves along a straight-line path away from the center of the circle. B) moves along a straight-line path toward the center of the circle. C) moves along a straight-line path in its original direction. D) continues to follow a circular path, but with a radius larger than the original radius. E) moves along a path that is neither straight nor circular.

C

57) When an object moves in uniform circular motion, the direction of its acceleration is A) in the same direction as its velocity vector. B) in the opposite direction of its velocity vector. C) is directed toward the center of its circular path. D) is directed away from the center of its circular path. E) depends on the speed of the object.

C

59) Two cars go around a banked curve at the proper speed for the banking angle. One car has tires with excellent traction, while the other car has bald slippery tires. Which of these cars is more likely to slide on the pavement as it goes around the curve? A) the car with the new tires B) the car with the bald tires C) Neither car will slide. D) It depends on if the pavement is wet or dry

C

62) You throw a baseball straight up. Compare the sign of the work done by gravity while the ball goes up with the sign of the work done by gravity while it goes down. A) The work is positive on the way up and positive on the way down. B) The work is positive on the way up and negative on the way down. C) The work is negative on the way up and positive on the way down. D) The work is negative on the way up and on the way down because gravity is always downward

C

66) Swimmers at a water park have a choice of two frictionless water slides, as shown in the figure. Although both slides drop over the same height h, slide 1 is straight while slide 2 is curved, dropping quickly at first and then leveling out. How does the speed v1 of a swimmer reaching the bottom of slide 1 compare with v2, the speed of a swimmer reaching the end of slide 2? 15 A) v1 > v2 B) v1 < v2 C) v1 = v2 D) The heavier swimmer will have a greater speed than the lighter swimmer, no matter which slide he uses. E) No simple relationship exists between v1 and v2.

C

75) Consider two less-than-desirable options. In the first you are driving 30 mph and crash headon into an identical car also going 30 mph. In the second option you are driving 30 mph and crash head-on into a stationary brick wall. In neither case does your car bounce back from the thing it hits, and the collision time is the same in both cases. Which of these two situations would result in the greater impact force on your car? A) hitting the other car B) hitting the brick wall C) The force would be the same in both cases. D) None of the above choices are correct.

C

24) The motions of a car and a truck along a straight road are represented by the velocity-time graphs in the figure. The two vehicles are initially alongside each other at time t = 0. At time T, what is true of the distances traveled by the vehicles since time t = 0? A) They will have traveled the same distance. B) The truck will not have moved. C) The car will have travelled further than the truck. D) The truck will have travelled further than the car.

D

33) An object is moving with constant non-zero velocity. Which of the following statements about it must be true? A) A constant force is being applied to it in the direction of motion. B) A constant force is being applied to it in the direction opposite of motion. C) A constant force is being applied to it perpendicular to the direction of motion. D) The net force on the object is zero. E) Its acceleration is in the same direction as it velocity.

D

37) While flying horizontally in an airplane, you notice that a string dangling from the overhead luggage compartment hangs at rest at 15° away from the vertical toward the front of the plane. Using this observation, you can conclude that the airplane is A) moving forward. B) moving backward. C) accelerating forward. D) accelerating backward. E) not accelerating because the string is at rest

D

41) An object is moving with constant non-zero velocity. Which of the following statements about it must be true? A) A constant force is being applied to it in the direction of motion. B) A constant force is being applied to it in the direction opposite of motion. C) A constant force is being applied to it perpendicular to the direction of motion. D) The net force on the object is zero. E) Its acceleration is in the same direction as it velocity.

D

44) A fireman is sliding down a fire pole. As he speeds up, he tightens his grip on the pole, thus increasing the vertical frictional force that the pole exerts on the fireman. When the force on his hands equals his weight, what happens to the fireman? A) The fireman comes to a stop. B) The fireman descends with slower and slower speed. C) The fireman descends with a smaller but non-zero acceleration. D) The fireman continues to descend, but with constant speed. E) The acceleration of the fireman is now upward

D

45) A 75-N box rests on a perfectly smooth horizontal surface. The minimum force need to start the box moving is A) 75 N. B) 7.5 N. C) 750 N. D) any horizontal force greater than zero.

D

5) An object moving in the +x direction experiences an acceleration of +2.0 m/s2. This means the object A) travels 2.0 m in every second. B) is traveling at 2.0 m/s. C) is decreasing its velocity by 2.0 m/s every second. D) is increasing its velocity by 2.0 m/s every second.

D

53) A push of magnitude P acts on a box of weight W as shown in the figure. The push is directed at an angle θ below the horizontal, and the box remains a rest. The box rests on a horizontal surface that has some friction with the box. The normal force on the box due to the floor is equal to PICTURE A) W. B) W + P. C) W + P cos θ. D) W + P sin θ. E) W - P sin θ.

D

56) A car goes around a circular curve on a horizontal road at constant speed. What is the 13 direction of the friction force on the car due to the road? A) tangent to the curve in the forward direction B) tangent to the curve opposite to the direction of the car's motion C) perpendicular to the curve outward D) perpendicular to the curve inward E) There is no friction on the car because its speed is constant.

D

60) A spaceship is traveling to the Moon. At what point is it beyond the pull of Earth's gravity? A) when it gets above the atmosphere B) when it is half-way there C) when it is closer to the Moon than it is to Earth D) It is never beyond the pull of Earth's gravity.

D

65) A stone is held at a height h above the ground. A second stone with four times the mass of the first one is held at the same height. The gravitational potential energy of the second stone compared to that of the first stone is A) one-fourth as much. B) one-half as much. C) twice as much. D) four times as much. E) the same.

D

67) Two frisky otters slide down frictionless hillsides of the same height but different slopes. The slope of the hill of otter 1 is 30°, while the slope of the hill of otter 2 is 60°. If both start from rest, which otter is moving faster when she reaches the bottom of her hill? A) Otter 1 is moving faster. B) Otter 2 is moving faster. C) The heavier otter is moving faster, no matter which hill she used. D) Both otters have the same speed at the bottom. E) The otter that took the shorter time is moving faster

D

72) If the units of your answer are kg ∙ m2/s3, which of the following types of quantities could your answer be? (There could be more than one correct choice.) A) kinetic energy B) potential energy C) force D) power E) work

D

8) Suppose that an object is moving with a constant velocity. Which statement concerning its acceleration must be correct? A) The acceleration is constantly increasing. B) The acceleration is constantly decreasing. C) The acceleration is a constant non-zero value. D) The acceleration is equal to zero.

D

28) Which of the following statements are true about an object in two-dimensional projectile motion with no air resistance? (There could be more than one correct choice.) A) The speed of the object is constant but its velocity is not constant. B) The acceleration of the object is +g when the object is rising and -g when it is falling. C) The acceleration of the object is zero at its highest point. D) The speed of the object is zero at its highest point. E) The horizontal acceleration is always zero and the vertical acceleration is always a non-zero constant downward.

E

39) A crate is sliding down an inclined ramp at a constant speed of 0.55 m/s. The vector sum of all the forces acting on this crate must point A) down the ramp. B) up the ramp. C) perpendicular to the ramp. D) vertically downward. E) None of the above choices is correct

E

71) A heavy dart and a light dart are launched vertically by identical ideal springs. Both springs were initially compressed by the same amount. There is no significant air resistance. Which of the following statements about these darts are correct? (There could be more than one correct choice.) A) The heavy dart goes higher than the light dart. B) The light dart goes higher than the heavy dart. C) Both darts reach the same maximum height. D) At the maximum height, both darts have the same gravitational potential energy. E) Both darts began moving upward with the same initial speed.

B,D

48) When a 45-kg person steps on a scale in an elevator, the scale reads a steady 410 N. Which of the following statements must be true? (There could be more than one correct choice.) A) The elevator is accelerating upward at a constant rate. B) The elevator is accelerating downward at a constant rate. C) The elevator is moving upward at a constant rate. D) The elevator is moving downward at a constant rate. E) From the given information, we cannot tell if the elevator is moving up or down.

B,E

69) A heavy rock and a light rock are dropped from the same height and experience no significant air resistance as they fall. Which of the following statements about these rocks are correct? (There could be more than one correct choice.) A) Both rocks have the same kinetic energy when they reach the ground. B) Both rocks have the same speed when they reach the ground. C) The heavier rock reaches the ground before the lighter rock. D) Just as they were released, both rocks had the same amount of gravitational potential energy. E) When they reach the ground, the heavier rock has more kinetic energy than the lighter rock.

B,E

49) In the figure, a 10-lb weight is suspended from two spring scales, each of which has negligible weight. Which one of the following statements about the readings in the scales is true? PICTURE A) Each scale will read 5 lb. B) The top scale will read zero, the lower scale will read 10 lb. C) The lower scale will read zero, the top scale will read 10 lb. D) Each scale will show a reading between one and 10 lb, such that the sum of the two is 10 lb. However, exact readings cannot be determined without more information. E) None of these is true.

E

50) Two blocks, A and B, are being pulled to the right along a horizontal surface by a horizontal 100-N pull, as shown in the figure. Both of them are moving together at a constant velocity of 2.0 m/s to the right, and both weigh the same. PICTURE Which of the figures below shows a correct free-body diagram of the horizontal forces acting on the upper block, A? PICTURES A) B) C) D) E)

E

68) A lightweight object and a very heavy object are sliding with equal speeds along a level frictionless surface. They both slide up the same frictionless hill with no air resistance. Which object rises to a greater height? A) The heavy object, because it has greater initial kinetic energy. B) The light object, because gravity slows it down less. C) The lightweight object, because the force of gravity on it is less. D) The heavy object, because it has more mass to carry it up the hill. E) They both slide to exactly the same height.

E

74) A small car meshes with a large truck in a head-on collision. Which of the following statements concerning the momentum during the collision are correct? (There could be more than one correct choice.) A) The momentum of the truck is conserved. B) The momentum of the car is conserved. C) The car and the truck must undergo the same change in speed. D) The momentum of the car and the momentum of the truck are each conserved. E) The momentum of the car-truck system is conserved, but the momentum of each one 17 separately is not conserved.

E