Tennessee State University

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1 Tennessee State University Dept. of Physics & Mathematics PHYS 2010 CF SU 2009 Name 30% Time is 2 hours. Cheating will give you an F-grade. Other instructions will be given in the Hall. MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 1) The highest tides occur when 1) A) the Sun, Moon, and Earth form a right-angled triangle with Earth at the 90 vertex. B) the Sun, Moon, and Earth form a right-angled triangle with the Moon at the 90 vertex. C) the Sun, Moon, and Earth form a right-angled triangle with the Sun at the 90 vertex. D) the Sun and the Moon are on opposite sides of Earth. E) the Sun and the Moon are on the same side of Earth. 2) Neptune has a radius of m and an escape velocity of 23,300 m/s. What is the mass of Neptune? G = N m2/kg2. A) kg B) kg C) kg D) kg E) kg 2) 3) In 1851 Jean Bernard Leon Foucault demonstrated the rotation of the Earth using a pendulum 11.0 m long, which was set up in the Paris Observatory. What was the period of oscillation of the pendulum? A) 6.65 s B) 5.63 s C) 2.12 s D) 2.58 s E) 1.79 s 4) A sewing machine needle moves up and down in simple harmonic motion with an amplitude of 1.27 cm and a frequency of 2.55 Hz. How long does it take it to travel cm? A) s B) 1.13 s C) 1.76 s D) 2.65 s E) 3.53 s 3) 4) 5) The pitch of a sound is determined by 5) A) the amplitude. B) the wavelength. C) the speed. D) the frequency. E) none of the above 6) As you stand by the side of the road, a car approaches you at a constant speed, sounding its horn, and you hear a frequency of 76 Hz. After the car goes by, you hear a frequency of 65 Hz. What is the speed of the car? The speed of sound in air is 343 m/s. A) 30 m/s B) 27 m/s C) 29 m/s D) 26 m/s E) 28 m/s 6) 1

2 Figure ) A 10-kg sign is held by two ropes as shown in Figure What is the tension on rope A? 7) A) 44 N B) 88 N C) 98 N D) 72 N E) 69 N 8) An enclosed chamber with sound absorbing walls has a 2.0 m 1.0 m opening for an outside window. A loudspeaker is located outdoors, 56 m away and facing the window. The intensity level of the sound entering the window space from the loudspeaker is 80 db. Assume the acoustic output of the loudspeaker is uniform in all directions and that acoustic energy incident upon the ground is completely absorbed. The acoustic power entering through the window space, in µw, is closest to: A) 200 B) 400 C) 1000 D) 2000 E) 100 8) 9) A 50.0-kg box is being pushed along a horizontal surface. The coefficient of kinetic friction between the box and the ground is What horizontal force must be exerted on the box for it to accelerate at 1.20 m/s2? A) 232 N B) 60.0 N C) 172 N D) 116 N E) 491 N 9) 10) If the net work done on an object is negative, then the object's kinetic energy 10) A) decreases. B) remains the same. C) increases. D) is zero. E) cannot be determined without knowing the object mass. 11) A constant force of 20 N is applied to an object of mass 8.0 kg at an angle of 25 with the horizontal. What is the work done by this force on the object if it causes a displacement of 2.0 m along the horizontal direction? A) 17 J B) 0 J C) 36 J D) 19 J E) 40 J 11) 2

3 Figure 8-7 Two masses M1 = 2.0 kg and M2 = 4.0 kg are attached by a string as shown in Figure 8-7. M1 falls vertically down and M2 moves on a frictionless surface. Initially the system is at rest. Use g = 10 m/s2. 12) Refer to Figure 8-7. What is the speed of mass M1 just before it touches the ground? 12) A) 2.9 m/s B) 3.8 m/s C) 4.6 m/s D) 2.3 m/s E) 5.8 m/s 13) A wire, 3.0 m long, with a mass of 70 g, is under tension. A transverse wave is propagated on the wire, for which the frequency is 320 Hz, the wavelength is 0.90 m, and the amplitude is 6.5 mm. The time for a crest of the transverse wave to travel the length of the wire, in ms, is closest to: A) 10 B) 14 C) 13 D) 12 E) ) An object with a mass of 10 kg is moving along a horizontal surface. At a certain point it has a speed of 12 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) 18 m C) 61 cm D) 18 cm E) 23 m 15) 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 objects experiences the greater momentum change? A) the ball B) the putty C) Both experience the same non-zero momentum change. D) Both experience zero momentum change. E) Cannot be determined from the information given. 16) A 900-kg car traveling east at 15.0 m/s collides with a 750-kg car traveling north at 20.0 m/s. The cars stick together. What is the speed of the wreckage just after the collision? A) 6.10 m/s B) 35.0 m/s C) 12.2 m/s D) 17.3 m/s E) 25.0 m/s 17) Two children are riding on a merry-go-round. Child A is at a greater distance from the axis of rotation than child B. Which child has the larger tangential speed? A) Child A B) Child B C) They have the same zero tangential speed. D) They have the same non-zero tangential speed. E) There is not enough information given to answer the question. 13) 14) 15) 16) 17) 3

4 18) A wheel rotates through an angle of 13.8 rad as it slows down from 22.0 rad/s to 13.5 rad/s. What is the magnitude of the average angular acceleration of the wheel? A) 111 rad/s2 B) 5.45 rad/s2 C) rad/s2 D) 10.9 rad/s2 E) 22.5 rad/s2 18) Figure ) An 82.0 kg-diver stands at the edge of a light 5.00-m diving board, which is supported by two pillars 1.60 m apart, as shown in Figure Find the force exerted by pillar A. A) 1.71 kn downwards B) 3.44 kn upwards C) 2.51 kn upwards D) 2.51 kn downwards E) 1.71 kn upwards 20) A figure skater is spinning slowly with arms outstretched. She brings her arms in close to her body and her angular speed increases dramatically. The speed increase is a demonstration of A) conservation of energy: her moment of inertia is decreased, and so her angular speed must increase to conserve energy. B) conservation of angular momentum: her moment of inertia is decreased, and so her angular speed must increase to conserve angular momentum. C) Newton's second law for rotational motion: she exerts a torque and so her angular speed increases. D) This has nothing to do with mechanics, it is simply a result of her natural ability to perform. 21) Type A nerve fibers in humans can conduct nerve impulses at speeds up to 140 m/s. How fast are the nerve impulses in miles per hour? (1 mi = 1609 m and 1 hr = 3600 s). A) 276 B) 313 C) 410 D) 924 E) ) 20) 21) 22) When dividing several quantities, the number of significant digits in the result must always be 22) A) equal to the average number of significant digits in the most and least accurate of the quantities. B) equal to the number of significant digits in the least accurate of the quantities. C) equal to the number of significant digits in the most accurate of the quantities. D) larger than the number of significant digits in the most accurate of the quantities. E) smaller than the number of significant digits in the least accurate of the quantities. 4

5 23) You shoot an arrow into the air. After 3.4 seconds the arrow has gone straight upward to a height of 35.0 m above its launch point. Ignore air resistance. What was the arrow's initial speed? A) 21.7 m/s B) 9.81 m/s C) 119 m/s D) 27 m/s E) 1401 m/s 23) 24) The slope of a line connecting two points on a velocity versus time graph gives 24) A) instantaneous velocity. B) average velocity. C) displacement. D) average acceleration. E) instantaneous acceleration. 25) A car is traveling at 25 m/s when it runs off the road and hits a utility pole. The car stops instantly, but the driver continues to move forward at 25 m/s. The airbag starts from rest with a constant acceleration from a distance of 50 cm away from the driver and makes contact with him in 8 ms. What is the acceleration of the airbag? A) 94 m/s2 B) 940 m/s2 C) 9400 m/s2 D) m/s2 E) m/s2 25) 26) The x and y components of a vector r are rx = 14.5 m and ry = 8.3 m, respectively. Find the 26) direction and magnitude of the vector r. A) 20.8 and 22.7 m respectively B) 19.8 and 46.7 m respectively C) 10.8 and 17.7 m respectively D) 29.8 and 16.7 m respectively E) 42.8 and 13.7 m respectively 27) The sum of two vectors has the greatest magnitude when the angle between these two vectors is 27) A) 180. B) 90. C) 270. D) 0. E) ) A ball is thrown horizontally with an initial velocity of 20.0 m/s from the edge of a building of a certain height. The ball lands at a horizontal distance of 84.0 m from the base of the building. What is the height of the building? A) 87.9 m B) 60.2 m C) 40.5 m D) 86.4 m E) 50.4 m 28) 29) A constant net force acts on an object. Describe the motion of the object. 29) A) constant non-zero acceleration. B) zero acceleration. C) decreasing acceleration. D) constant non-zero velocity. E) increasing acceleration. 30) A 75 kg water skier floating in a lake is pulled from rest to a speed of 13 m/s in a distance of 25 m. What is the net force exerted on the skier, assuming his acceleration is constant? A) 254 N B) 390 N C) 325 N D) 1875 N E) 975 N 30) 5