MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.

Transcription

1 Common Quiz Mistakes / Practice for Final Exam Name MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 1) A ball is thrown directly upward and experiences no air resistance. Which one of the following statements about its motion is correct? A) The acceleration of the ball is downward while it is traveling up and downward while it is traveling down but is zero at the highest point when the ball stops. B) The acceleration of the ball is upward while it is traveling up and downward while it is traveling down. C) The acceleration is downward during the entire time the ball is in the air. D) The acceleration of the ball is downward while it is traveling up and upward while it is traveling down. 2) Jan and Len throw identical rocks off a tall building at the same time. The ground near the building is flat. Jan throws her rock straight downward. Len throws his rock downward and outward such that the angle between the initial velocity of the rock and the horizon is 30. Len throws the rock with a speed twice that of Jan's rock. If air resistance is negligible, which rock hits the ground first? A) Len's rock hits first. B) Jan's rock hits first. C) They hit at the same time. D) It is impossible to know from the information given. 3) While an object is in projectile motion (with upward being positive) with no air resistance, A) the horizontal component of its velocity remains constant and the vertical component of its acceleration is equal to -g. B) the vertical component of its velocity remains constant and the vertical component of its acceleration is equal to -g. C) the horizontal component of its velocity remains constant and the horizontal component of its acceleration is equal to -g. D) the horizontal component of its velocity remains constant and the vertical component of its acceleration is equal to zero. E) the vertical component of both its velocity and its acceleration remain constant. 1) 2) 3) 1

2 4) Point P in the figure indicates the position of an object traveling at constant speed clockwise around the circle. Which arrow best represents the direction of the acceleration of the object at point P? 4) A) B) C) D) E) 5) A book rests on a level table top. Which force does Newton's third law imply is equal in magnitude but opposite in direction to the weight of the book? A) the force of the table on the earth B) the force of the table on the book C) the force of the earth on the table D) the force of the book on the table E) the force of the book on the earth 5) 2

3 6) An object of mass m sits on a flat table. The Earth pulls on this object with force mg, which we will call the action force. What is the reaction force? A) The table pushing down on the floor with force mg. B) The object pushing down on the table with force mg. C) The object pulling upward on the Earth with force mg. D) The table pushing up on the object with force mg. E) The table pulling upward on the Earth with force mg. 6) 7) You ride on an elevator that is moving upward with constant speed while standing on a bathroom scale. The reading on the scale is A) more than your true weight, mg. B) less than your true weight, mg. C) equal to your true weight, mg. D) could be more or less than your true weight, mg, depending on the value of the speed. 8) A dog is standing in the bed of a pickup truck. The bed is coated with ice, causing the force of friction between the dog and the truck to be zero. The truck is initially at rest, and then accelerates to the right, moving along a flat road. As seen from a stationary observer (watching the truck move to the right), the dog A) moves to the right, but not as quickly as the truck is moving to the right, causing it to slide towards the back of the truck. B) does not move left or right, but the back of the truck moves towards the dog. C) moves to the right at the same rate as the truck, so it doesn't slide. D) moves to the left, as the truck moves to the right, causing the dog to slide towards the back of the truck. 9) The figure shows two 1.0 kg-blocks connected by a rope. A second rope hangs beneath the lower block. Both ropes have a mass of 250 g. The entire assembly is accelerated upward at 2.3 m/s 2 by force F. What is the tension at the top end of rope 1? 7) 8) 9) A) 18 N B) 15 N C) 3.5 N D) 2.9 N 3

4 10) Consider a plot of the displacement (x) as a function of the applied force (F) for an ideal elastic spring. The slope of the curve would be A) the reciprocal of the spring constant. B) the spring constant. C) the acceleration due to gravity. D) the reciprocal of the acceleration of gravity. E) the mass of the object attached to the spring. 11) A 3.00-kg ball swings rapidly in a complete vertical circle of radius 2.00 m by a light string that is fixed at one end. The ball moves so fast that the string is always taut and perpendicular to the velocity of the ball. As the ball swings from its lowest point to its highest point A) the work done on it by gravity is -118 J and the work done on it by the tension in the string is +118 J. B) the work done on it by gravity and the work done on it by the tension in the string are both equal to -118 J. C) the work done on it by gravity and the work done on it by the tension in the string are both equal to zero. D) the work done on it by gravity is +118 J and the work done on it by the tension in the string is -118 J. E) the work done on it by gravity is -118 J and the work done on it by the tension in the string is zero. 10) 11) SHORT ANSWER. Write the word or phrase that best completes each statement or answers the question. 12) Three cars (car F, car G, and car H) are moving with the same velocity when the driver suddenly slams on the brakes, locking the wheels. The most massive car is car F, the least massive is car H, and all three cars have identical tires. (a) Which car travels the longest distance to skid to a stop? A) Car F B) Car G C) Car H D) They all travel the same distance in stopping. 12) (b) For which car does friction do the largest amount of work in stopping the car? A) Car F B) Car G C) Car H D) The amount of work done by friction is the same for all cars. 4

5 MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 13) Two identical balls are thrown directly upward, ball A at speed v and ball B at speed 2v, and they feel no air resistance. Which statement about these balls is correct? A) At their highest point, the acceleration of each ball is instantaneously equal to zero because they stop for an instant. B) The balls will reach the same height because they have the same mass and the same acceleration. C) At its highest point, ball B will have twice as much gravitational potential energy as ball A because it started out moving twice as fast. D) Ball B will go twice as high as ball A because it had twice the initial speed. E) Ball B will go four times as high as ball A because it had four times the initial kinetic energy. 14) A kg ball traveling horizontally on a frictionless surface approaches a very massive stone at 20.0 m/s perpendicular to wall and rebounds with 70.0% of its initial kinetic energy. What is the magnitude of the change in momentum of the stone? A) kg m/s B) 3.00 kg m/s C) 18.4 kg m/s D) 1.63 kg m/s E) 14.0 kg m/s 15) A baseball is thrown vertically upward and feels no air resistance. As it is rising A) its kinetic energy is conserved, but its momentum is not conserved. B) its gravitational potential energy is not conserved, buts its momentum is conserved. C) both its momentum and its mechanical energy are conserved. D) its momentum is not conserved, but its mechanical energy is conserved. E) both its momentum and its kinetic energy are conserved. 16) A shell explodes into two fragments, one fragment 25 times heavier than the other. If any gas from the explosion has negligible mass, then A) the kinetic energy change of the heavier fragment is 25 times as great as the kinetic energy change of the lighter fragment. B) the kinetic energy change of the lighter fragment is 25 times as great as the kinetic energy change of the heavier fragment. C) the momentum change of the heavier fragment is 25 times as great as the momentum change of the lighter fragment. D) the momentum change of the lighter fragment is exactly the same as the momentum change of the heavier fragment. E) the momentum change of the lighter fragment is 25 times as great as the momentum change of the heavier fragment. 13) 14) 15) 16) 5

6 17) A small car has a head-on collision with a large truck. Which of the following statements concerning the magnitude of the average force due to the collision is correct? A) The small car and the truck experience the same average force. B) The small car experiences the greater average force. C) The truck experiences the greater average force. D) It is impossible to tell since the masses are not given. E) It is impossible to tell since the velocities are not given. 18) A piece of thin uniform wire of mass m and length 3b is bent into an equilateral triangle. Find the moment of inertia of the wire triangle about an axis perpendicular to the plane of the triangle and passing through one of its vertices. A) 7 4 mb2 B) 1 2 mb2 C) 1 3 mb2 D) 2 3 mb2 7 E) 12 mb 19) When a rigid body rotates about a fixed axis, all the points in the body have the same A) angular acceleration. B) tangential acceleration. C) tangential speed. D) centripetal acceleration. E) linear displacement. 20) A solid sphere, solid cylinder, and a hollow pipe all have equal masses and radii and are of uniform density. If the three are released simultaneously at the top of an inclined plane and roll without slipping, which one will reach the bottom first? A) solid cylinder B) hollow pipe C) solid sphere D) They all reach the bottom at the same time. 21) A uniform disk, a uniform hoop, and a uniform solid sphere are released at the same time at the top of an inclined ramp. They all roll without slipping. In what order do they reach the bottom of the ramp? A) disk, hoop, sphere B) hoop, disk, sphere C) sphere, disk, hoop D) hoop, sphere, disk E) sphere, hoop, disk 22) If the torque on an object adds up to zero A) the forces on it also add up to zero. B) the object could be accelerating linearly but it could not be turning. C) the object is at rest. D) the object could be both turning and accelerating linearly. E) the object cannot be turning. 2 17) 18) 19) 20) 21) 22) 6

7 23) A nonuniform, 80.0-g, meterstick balances when the support is placed at the mark. At what location on the meterstick should a 5.00-g tack be placed so that the stick will balance at the 50.0 mark? A) 35.0 B) 67.0 C) 66.0 D) 16.0 E) ) Planet Z-34 has a mass equal to 1/3 that of Earth, a radius equal to 1/3 that of Earth, and an axial spin rate 1/2 that of Earth. With g representing, as usual, the acceleration due to gravity on the surface of Earth, the acceleration due to gravity on the surface of Z-34 is A) g/9. B) 3g. C) 9g. D) 6g. E) g/3. 25) A satellite in a circular orbit of radius R around planet X has an orbital period T. If Planet X had one-fourth as much mass, the orbital period of this satellite in an orbit of the same radius would be A) T/2. B) T 2 C) 4T. D) T/4. E) 2T. 23) 24) 25) 7

8 Answer Key Testname: COMMONMISTAKES 1) C 2) C 3) A 4) E 5) E 6) C 7) C 8) B 9) A 10) A 11) E 12) (a) D (b) A 13) E 14) C 15) D 16) D 17) A 18) B 19) A 20) C 21) C 22) D 23) E 24) B 25) E 8