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PHY 110 College Physics I Spring 2010 Final Review Name___________________________________ MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 1) A 0.140 kg baseball is thrown with a velocity of 28.9 m/s. It is struck with an average force of 5000.0 N, which results in a velocity of 37.0 m/s in the opposite direction. How long were the bat and ball in contact? A) 3.17 × 10-2 s 1) B) 1.85 × 10-3 s C) 1.32 × 10-2 s D) 4.44 × 10-3 s 2) A 1200 kg ore cart is rolling at 10.8 m/s across a flat surface. A crane dumps 858 kg of ore (vertically) into the cart. How fast does the cart move after being loaded with ore? Assume that frictional forces with the flat surface may be neglected. A) 3.8 m/s B) 6.3 m/s C) 4.2 m/s D) 5.7 m/s 2) Figure 8.2 3) A block of mass m = 3.6 kg, moving on a frictionless surface with a speed vi = 9.3 m/s, makes a perfectly elastic collision with a block of mass M at rest. After the collision, the 3.6 kg block recoils with a speed of vf = 2.7 m/s. In Figure 8.2, the speed of the block of mass M after the collision is closest to: A) 9.3 m/s B) 10.7 m/s C) 8.0 m/s D) 12.0 m/s E) 6.6 m/s 1 3) Figure 8.7 4) In Figure 8.7, four point masses are placed as shown. The x- and y-coordinates of the center of mass are closest to: A) (2.3, 2.7) B) (2.2, 2.6) C) (2.3, 2.6) D) (2.3, 2.8) E) (2.2, 2.7) 4) 5) A child is sitting on the outer edge of a merry-go-round that is 18 m in diameter. If the merry-go-round makes 4.9 rev/min, what is the velocity of the child in m/s? A) 3.2 m/s B) 4.6 m/s C) 0.7 m/s D) 9.2 m/s 5) 6) At time t = 0 s, a wheel has an angular displacement of zero radians and an angular velocity of +30 rad/s. The wheel has a constant acceleration of -0.48 rad/s2 . In this situation, the average 6) angular velocity in the interval from t = 0 s to t = 20 s is closest to: A) 28 rad/s B) 16 rad/s C) 15 rad/s D) 25 rad/s E) 20 rad/s 2 Figure 9.1 Point P is on the rim of a wheel of radius 2.0 m. At time t = 0, the wheel is at rest, and P is on the x-axis. The wheel undergoes a uniform angular acceleration of 0.01 rad/s2 about the center O. 7) In Figure 9.1, the time t, when P returns to the original position on the x-axis, is closest to: A) 18 s B) 50 s C) 25 s D) 35 s E) 13 s 7) 8) A solid, uniform sphere of mass 2.0 kg and radius 1.7 m rolls without slipping down an inclined plane of height 5.3 m. What is the angular velocity of the sphere at the bottom of the inclined plane? A) 8.7 rad/s B) 6.1 rad/s C) 9.7 rad/s D) 5.1 rad/s 8) 9) A 95 N force exerted at the end of a 0.32 m long torque wrench gives rise to a torque of 15 N · m. What is the angle (assumed to be less than 90°) between the wrench handle and the direction of the applied force? A) 30° B) 42° C) 36° D) 24° 9) Figure 10.4 10) In Figure 10.4, a given force F is applied to a rod in several different ways. In which case is the torque due to F about the pivot P greatest? A) 5 B) 2 C) 1 D) 3 E) 4 3 10) 11) A uniform, solid flywheel of radius 1.4 m and mass 15 kg rotates at 2.7 rad/s. What is the magnitude of the flywheel's angular momentum? A) 20 kg·m 2/s 11) B) 40 kg·m 2/s C) 60 kg·m 2/s D) 80 kg·m 2/s Figure 10.13 12) In Figure 10.13, what mass M is required to balance the mobile? A) 36 g B) 18 g C) 90 g D) 30 g E) 60 g 12) Figure 10.16 A 20 kg uniform door has a width of 1.2 m and a height of 2.5 m. The door is mounted on a post by a pair of hinges, marked 1 and 2, at the top and bottom of the door. An external force of 60 N, at an angle of 30° above the horizontal, is applied to the doorknob, as shown. The doorknob is 1.0 m above the bottom of the door. 13) In Figure 10.16, the x-component of the force, exerted on the door at the bottom by hinge 2, is closest to: A) +29 N B) +65 N C) -29 N D) zero E) -65 N 4 13) 14) A mass of 385 g hangs from one end of a string that goes over a pulley with a moment of inertia of 0.0125 kg·m 2 and a radius of 15.0 cm. A mass of 710 g hangs from the other end. When the masses 14) are released, the larger mass accelerates downward, the lighter mass accelerates upward, and the pulley turns without the string slipping on the pulley. What is the tension in the string on the side of the 710-g mass? A) 6.87 N B) 5.59 N C) 3.68 N D) 4.41 N E) 9.77 N Figure 11-9 15) The L-shaped object shown in Figure 11-9 consists of the masses connected by light rods. How much work must be done to accelerate the object from rest to an angular speed of 3.25 rad/s about the x-axis? A) 34.2 J B) 17.6 J C) 47.4 J D) 23.7 J E) 62.3 J 15) 16) A spaceship with a mass of 2.8 × 106 kg is traveling toward two asteroids, each with a mass of 5.0 × 1016 kg, which are 40 km apart. Its path is perpendicular to the line joining the asteroids and aimed 16) at the midpoint of that line. What is the net gravitational force exerted by the asteroids on the spaceship when the spaceship is 30 km away from that midpoint? G = 6.67 × 10 -11 N·m 2/kg2 . A) 18,000 N B) 12,000 N C) 8000 N D) 16,000 N E) 6200 N 17) Vector A = 6.0 m and points 30° south of east. Vector B = 4.0 m and points 30° east of south. The resultant vector A + B is given by A) 4.7 m at an angle 42° south of east. B) 1.1 m at an angle 42° south of east. C) 0.7 m at an angle 42° south of east. D) 9.7 m at an angle 42° south of east. E) 13.7 m at an angle 42° south of east. 5 17) 18) Three boxes rest side-by-side on a smooth, horizontal floor. Their masses are 5.0 kg, 3.0 kg, and 2.0 kg, with the 3.0-kg mass in the center. A force of 50 N pushes on the 5.0-kg mass, which pushes against the other two masses. What is the contact force between the 3.0-kg mass and the 2.0-kg mass? A) 0 N B) 25 N C) 10 N D) 50 N E) 40 N 18) Figure 8-6 A roller coaster of mass 80.0 kg is moving with a speed of 20.0 m/s at position A as shown in Figure 8-6. The vertical height at position A above ground level is 200 m. Neglect friction and use g = 10.0 m/s2 . 19) What is the speed of the roller coaster at point C? A) 34.6 m/s B) 69.2 m/s C) 20.0 m/s D) 0 m/s E) There is not enough information to solve this problem. 19) 20) An object of mass 2.00 kg starts at rest from the top of a rough inclined plane of height 20.0 m as shown in Figure 8-8. If the work done by the force of friction is -150 J, what is the speed of the object as it reaches the bottom of the inclined plane? Use g = 10.0 m/s2 . 20) A) 200 m/s B) 150 m/s C) 20.0 m/s D) 10.0 m/s E) 15.8 m/s 21) An object with a mass of 10 kg is moving along a horizontal surface. At a certain point it has a speed of 28 m/s. If the coefficient of friction between the object and the surface is 0.40, how far will the object go before it comes to a stop? Use g = 10 m/s2 . A) 61 m B) 61 cm C) 98 cm D) 23 m E) 98 m 6 21) Answer Key Testname: PHY110S10REVIEW 1) B 2) B 3) E 4) D 5) B 6) D 7) D 8) D 9) A 10) C 11) B 12) A 13) D 14) B 15) A 16) B 17) D 18) C 19) A 20) E 21) E 7