Name: __________________________ Date: _____________ 1. The work done by gravity during the descent of a projectile is: positive 2. A 1-kg block is lifted vertically 1 m by a boy. The work done by the boy is about: 10 J 3. A man wishes to pull a crate 15 m across a rough floor by exerting a force of 100 N. The coefficient of kinetic friction is 0.25. For the man to do the least work, the angle between the force and the horizontal should be: 0 4. An ideal spring is hung vertically from the ceiling. When a 2.0-kg mass hangs at rest from it the spring is extended 6.0 cm from its relaxed length. A downward external force is now applied to the mass to extend the spring an additional 10 cm. While the spring is being extended by the force, the work done by the spring is: 3.6 J 5. The weight of an object on the moon is one-sixth of its weight on the Earth. The ratio of the kinetic energy of a body on the Earth moving with speed V to that of the same body moving with speed V on the moon is: 1:1 6. Two objects with masses, m1 and m2, have the same kinetic energy and are both moving to the right. The same constant force is applied to the left to both masses. If m1 = 4m2, the ratio of the stopping distance of m1 to that of m2 is: 1:1 7. A particle starts from rest at time t = 0 and moves along the x axis. If the net force on it is proportional to t, its kinetic energy is proportional to: t4

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8. Which of the following five units represents a quantity that is NOT the same as the other four? A) joule B) erg C) watt D) foot pound E) newton meter 9. An escalator is used to move 20 people (60 kg each) per minute from the first floor of a department store to the second floor, 5 m above. The power required is approximately:

1000 W 10. A good example of kinetic energy is provided by: A) a wound-up clock spring B) the raised weights of a grandfather's clock C) a tornado D) a gallon of gasoline E) an automobile storage battery 11. A golf ball is struck by a golf club and falls on a green eight feet above the tee. The potential energy of the Earth-ball system is greatest: A) just before the ball is struck B) just after the ball is struck C) just after the ball lands on the green D) when the ball comes to rest on the green E) when the ball reaches the highest point in its flight 12. A 2.2-kg block starts from rest on a rough inclined plane that makes an angle of 25 with the horizontal. The coefficient of kinetic friction is 0.25. As the block goes 2.0 m down the plane, the mechanical energy of the Earth-block system changes by: 9.8 J

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13. An ideal spring is used to fire a 15.0-g block horizontally across a frictionless table top. The spring has a spring constant of 20 N/m and is initially compressed by 7.0 cm. The speed of the block as it leaves the spring is: 2.6 m/s 14. A toy cork gun contains a spring whose spring constant is 10.0 N/m. The spring is compressed 5.00 cm and then used to propel a 6.00-g cork. The cork, however, sticks to the spring for 1.00 cm beyond its unstretched length before separation occurs. The muzzle velocity of this cork is:

2.00 m/s 15. A ball of mass m, at one end of a string of length L, rotates in a vertical circle just fast enough to prevent the string from going slack at the top of the circle. The speed of the ball at the bottom of the circle is:

A) 2 gL B) 3 gL C) 4 gL D) 5 gL E) 7 gL

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16. Three identical blocks move either on a horizontal surface, up a plane, or down a plane, as shown below. They all start with the same speed and continue to move until brought to rest by friction. Rank the three situations according to the mechanical energy dissipated by friction, least to greatest.

2, 1, 3 17. A machinist starts with three identical square plates but cuts one corner from one of them, two corners from the second, and three corners from the third. Rank the three plates according to the x coordinates of their centers of mass, from smallest to largest.

1 and 3 tie, then 2 18. The center of mass of a system of particles has a constant velocity if: A) the forces exerted by the particles on each other sum to zero B) the external forces acting on particles of the system sum to zero C) the velocity of the center of mass is initially zero D) the particles are distributed symmetrically around the center of mass E) the center of mass is at the geometric center of the system

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19. A 2.0-kg block is attached to one end of a spring with a spring constant of 100 N/m and a 4.0-kg block is attached to the other end. The blocks are placed on a horizontal frictionless surface and set into motion. At one instant the 2.0-kg block is observed to be traveling to the right with a speed of 0.50 m/s and the 4.0-kg block is observed to be traveling to the left with a speed of 0.30 m/s. Since the only forces on the blocks are the force of gravity, the normal force of the surface, and the force of the spring, we conclude that: A) the spring is compressed at the time of the observation B) the spring is not compressed at the time of observation C) the motion was started with the masses at rest D) the motion was started with at least one of masses moving E) the motion was started by compressing the spring 20. A 1.0 kg-ball moving at 2.0 m/s perpendicular to a wall rebounds from the wall at 1.5 m/s. The change in the momentum of the ball is: 3.5 N s away from wall 21. A projectile in flight explodes into several fragments. The total momentum of the fragments immediately after this explosion: A) is the same as the momentum of the projectile immediately before the explosion B) has been changed into kinetic energy of the fragments C) is less than the momentum of the projectile immediately before the explosion D) is more than the momentum of the projectile immediately before the explosion E) has been changed into radiant energy 22. A cart loaded with sand slides forward along a horizontal frictionless track. As the cart moves, sand trickles out at a constant rate through a hole in the back of the cart. The acceleration of the cart is: A) constant and in the forward direction B) constant and in the backward direction C) variable and in the forward direction D) variable and in the backward direction E) zero

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23. Sphere X, of mass 2 kg, is moving to the right at 10 m/s. Sphere Y, of mass 4 kg, is moving to the left at 10 m/s. The two spheres collide head-on. The ratio of the magnitude of the impulse exerted by X on Y to that exerted by Y on X is: A) 1/4 B) 1/2 C) 1 2 D) 1 E) need to know whether the collision is elastic or inelastic 24. A ball hits a wall and rebounds with the same speed, as diagrammed below. The changes in the components of the momentum of the ball are:

A) B) C) D) E)

px > 0, px < 0, px = 0, px = 0, px > 0,

py > 0 py > 0 py > 0 py < 0 py < 0

25. A 3.00-g bullet traveling horizontally at 400 m/s hits a 3.00-kg wooden block, which is initially at rest on a smooth horizontal table. The bullet buries itself in the block without passing through. The speed of the block after the collision is: 0.40 m/s 26. An elastic collision is one in which: A) momentum is not conserved but kinetic energy is conserved B) total mass is not conserved but momentum is conserved C) kinetic energy and momentum are both conserved D) momentum is conserved but kinetic energy is not conserved E) the total impulse is equal to the change in kinetic energy 27. Two objects, X and Y, are held at rest on a horizontal frictionless surface and a spring is compressed between them. The mass of X is 2/5 times the mass of Y. Immediately after the spring is released, X has a kinectic energy of 50 J and Y has a kinetic erengy of: 125 J

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28. The angular speed of the second hand of a watch is: ( /30) m/s 29. The angular velocity of a rotating wheel increases 2 rev/s every minute. The angular acceleration, in rad/s2 of this wheel is: 2 /30 30. A wheel starts from rest and has an angular acceleration that is given by (t) = 6rad/s4)t2. The angle through which it turns in time t is given by: [(1/2)t4] rad 31. The figure shows a cylinder of radius 0.7 m rotating about its axis at 10 rad/s. The speed of the point P is:

7.0 m/s 32. A flywheel of diameter 1.2 m has a constant angular acceleration of 5.0 rad/s2. The tangential acceleration of a point on its rim is: 6.0 m/s2 33. Three identical balls are tied by light strings to the same rod and rotate around it, as shown below. Rank the balls according to their rotational inertia, least to greatest.

A) B) C) D) E)

1, 2, 3 3, 2, 1 3, then 1 and 2 tie 1, 3, 2 All are the same

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34. Two uniform circular disks having the same mass and the same thickness are made from different materials. The disk with the smaller rotational inertia is: A) the one made from the more dense material B) the one made from the less dense material C) neither both rotational inertias are the same D) the disk with the larger angular velocity E) the disk with the larger torque 35. A force with a given magnitude is to be applied to a wheel. The torque can be maximized by: A) applying the force near the axle, radially outward from the axle B) applying the force near the rim, radially outward from the axle C) applying the force near the axle, parallel to a tangent to the wheel D) applying the force at the rim, tangent to the rim E) applying the force at the rim, at 45 to the tangent 36. A cylinder is 0.10 m in radius and 0.20 in length. Its rotational inertia, about the cylinder axis on which it is mounted, is 0.020 kg m2. A string is wound around the cylinder and pulled with a force of 1.0 N. The angular acceleration of the cylinder is: 5.0 rad/s2 37. A 8.0-cm radius disk with a rotational inertia of 0.12 kg m2 is free to rotate on a horizontal axis. A string is fastened to the surface of the disk and a 10-kg mass hangs from the other end. The mass is raised by using a crank to apply a 9.0-N m torque to the disk. The acceleration of the mass is: 0.50 m/s2 38. A disk with a rotational inertia of 5.0 kg m2 and a radius of 0.25 m rotates on a fixed axis perpendicular to the disk and through its center. A force of 2.0 N is applied tangentially to the rim. As the disk turns through half a revolution the work done by the force is: 1.6 J 39. The coefficient of static friction between a certain cylinder and a horizontal floor is 0.40. If the rotational inertia of the cylinder about its symmetry axis is given by I = (1/2)MR2, then the maximum acceleration the cylinder can have without sliding is: 0.8 g

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40. When we apply the energy conversation principle to a cylinder rolling down an incline without sliding, we exclude the work done by friction because: A) there is no friction present B) the angular velocity of the center of mass about the point of contact is zero C) the coefficient of kinetic friction is zero D) the linear velocity of the point of contact (relative to the inclined surface) is zero E) the coefficient of static and kinetic friction are equal 41. The newton second is a unit of: A) work B) angular momentum C) power D) linear momentum E) none of these 42. A 2.0-kg block travels around a 0.50-m radius circle it has an angular speed of 12 rad/s. The circle is parallel to the xy plane and is centered on the z axis, 0.75 m from the origin. The magnitude of its angular momentum around the origin is: 11 kg m2/s 43. A 2.0-kg stone is tied to a 0.50-m string and swung around a circle at a constant angular velocity of 12 rad/s. The torque on the stone about the center of the circle is: 0 44. A man, with his arms at his sides, is spinning on a light frictionless turntable. When he extends his arms: A) his angular velocity increases B) his angular velocity remains the same C) his rotational inertia decreases D) his rotational kinetic energy increases E) his angular momentum remains the same

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45. A phonograph record is dropped onto a freely spinning turntable. Then: A) neither angular momentum nor mechanical energy is conserved because of the frictional forces between record and turntable B) the frictional force between record and turntable increases the total angular momentum C) the frictional force between record and turntable decreases the total angular momentum D) the total angular momentum remains constant E) the sum of the angular momentum and rotational kinetic energy remains constant 46. The center of gravity coincides with the center of mass: A) always B) never C) if the center of mass is at the geometrical center of the body D) if the acceleration due to gravity is uniform over the body E) if the body has a uniform distribution of mass 47. Three identical uniform rods are each acted on by two or more forces, all perpendicular to the rods. Which of the rods could be in static equilibrium if an additional force is applied at the center of mass of the rod?

A) B) C) D) E)

Only 1 Only 2 Only 3 Only 1 and 2 All three

48. A 5.0 m weightless strut, hinged to a wall, is used to support a 800-N block as shown. The horizontal and vertical components of the force of the hinge on the strut are:

FH = 600 N, FY = 800 N

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49. A window washer attempts to lean a ladder against a frictionless wall. He finds that the ladder slips on the ground when it is placed at an angle of less than 75 to the ground but remains in place when the angle is greater than 75. The coefficient of static friction between the ladder and the ground: A) is about 0.13 50. A 400-N uniform vertical boom is attached to the ceiling by a hinge, as shown. An 800N weight W and a horizontal guy wire are attached to the lower end of the boom as indicated. The pulley is massless and frictionless. The tension force T of the horizontal guy wire has magnitude:

400 N 51. Young's modulus is a proportionality constant that relates the force per unit area applied perpendicularly at the surface of an object to: A) the shear B) the fractional change in volume C) the fractional change in length D) the pressure E) the spring constant 52. The bulk modulus is a proportionality constant that relates the pressure acting on an object to: A) the shear B) the fractional change in volume C) the fractional change in length D) Young's modulus E) the spring constant

Answer Key1. 2. 3. 4. A C A APage 11

5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27. 28. 29. 30. 31. 32. 33. 34. 35. 36. 37. 38. 39. 40. 41. 42. 43. 44. 45. 46. 47. 48. 49. 50.

C E C C C C E B E C D E E B D D A E D C B C D C D C A D A A D B A A D D D C A E D D C B A B

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51. C 52. B

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