Unformatted text preview: UCSD Physics 2A Winter 2009 Instructor : Prof. Vivek Sharma Final Exam (Section A) INSTRUCTIONS: Fill, tear and return the bottom strip of the front page with your scantron. Seperately, return back rest of the exam sheets. Use a #2 pencil to fill your scantron. Write your code number and bubble it in under ““EXAM NUMBER””. Bubble in the exam version (see letter AH at bottom of page) in your scantron under ““TEST VERSION””. MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 1) A boat, whose speed in still water is 2.70m/s, must cross a 280m wide river and arrive at a point 120m upstream from where it starts. To do so the pilot must head the boat at a 45 o upstream angle. What ʹs the speed of the riverʹs current? A) 1.10 m/s 2) B)  1.10 m/s C) 0.67 m/s D) 2.07m/s E) 2.70 m/s A small block of mass m = 1kg rests on the sloping side of a triangular block of mass M =10 kg. The angle θ=30o. The block M itself rests on a horizontal frictionless table. Assuming all surfaces are frictionless, what is the magnitude of the force F that must be applied to M so that m remains in a fixed position relative to M? A) 62 N B) 108 N C) 56 N D) 6 N E) 17 N Tear here and submit strip along with the scantron card. Follow TA instructionsName____________________________________________CodeNumber___________________ Final Exam (Section A) Version A‐1 UCSD Physics 2A Winter 2008 Instructor : Vivek Sharma Final Exam (Section A)
3) A basketball is shot from an initial height of 2.4m with an intial speed of 12m/s directed at an angle + 35o above the horizontal. At what angle to the horizontal did the ball enter the basket? A)  20o B) 31o C)  31o D) 0 o E) 20o 4) An object is hanging by a string from your rearview mirror. While you are accelerating at a constant rate from rest to 28 m/s in 6.0 s, what angle θ does the string make with the vertical? A) 15 o B) 5 o C) 35 o D) 25 o E) 60 o Final Exam (Section A) Version A‐2 UCSD Physics 2A Winter 2008 Instructor : Vivek Sharma Final Exam (Section A)
5) A 3.0 kg block sits on top of a 5.0 kg block which is on a horizontal surface. The 5.0 kg block is pulled to the right with a force F as shown. The coefficient of static friction between all surfaces is 0.6 and the coefficient of kinetic friction is 0.40. What is the minimum value of F needed to move the two blocks? A) 47 N B) 78 N C) 41 N D) 82 N E) 137 N 6) A 1.34 kg ball is connected by means of two massless strings, each of length L = 1.70 m, to a vertical rotating rod. The strings are tied to the rod with seperation d = 1.70 m and are taut. The tension in the upper string is 35 N. What is the speed of the ball? A) 6.45 m/s B) 6.73 m/s C) 12.90 m/s D) 13.5 m/s E) 10.1 m/s 7) A 920 kg sports car collides into the rear end of a 2300 kg SUV stopped at a red light. The bumpers lock, brakes are locked and the two cars skid forward 2.8m before stopping. The police officer estimates the coefficient of kinetic friction between tires and the road to be 0.80. What was the speed of the sports car at impact? A) 529 m/s B) 10 m/s C) 12 m/s D) 920 m/s E) 23 m/s Final Exam (Section A) Version A‐3 UCSD Physics 2A Winter 2008 Instructor : Vivek Sharma Final Exam (Section A)
8) In the track shown above, the section AB is one quadrant of a circle of radius 2.0m and is frictionless. Section BC is a horizontal span 3.0 m long and with a coefficient of kinetic friction of 0.25. The section CD under the spring is frictionless. A block of mass 1.0 kg is released from rest at A. After sliding on the track, it compresses the spring by 20cm. What is the velocity of the block at point C ? A) 7.3 m/s B) 2.1 m/s C) 6.3 m/s D) 4.9m/s E) 9.7 m/s 9) A piece of thin wire of mass m and length 3a is bent into an equilateral triangle. Find the moment of inertia of the wire when it is rotating about an axis perpendicular to the plane of the triangle and passing through one of its vertices. 2 1 7 3 1 B) ma2 C) ma2 D) ma2 E) ma2 A) ma2 3 2 4 2 3 10) A uniform solid sphere of radius R and moment of Inertia I = (2/5)MR2 is set rotating about a horizontal axis at an angular speed ω0 and is then placed on the floor with its center of mass at rest. If the coefficient of kinetic friction between the sphere and the floor is μ, the speed v of the center of mass of the sphere when the sphere begins to roll without slipping is equal to: A) (2/5)ω 0 R B) ω0 R C) (2/7)(1/μ)ω0 R D) (2/7)μω0 R E) (2/7)ω 0 R Final Exam (Section A) Version A‐4 UCSD Physics 2A Winter 2008 Instructor : Vivek Sharma Final Exam (Section A)
11) In the figure above, an 80 kg man is on a long rope ladder hanging from a balloon that has a total mass of 320 kg (including the basket passenger ). The balloon is initially stationary relative to the ground . When the man on the ladder begins to climb at 2.5 m/s relative to the ladder , whatʹs the velocity of the balloon relative to ground ? A) 0.63 m/s up B) Ballon will remain stationary C) 0.24 m/s down D) 0.63 m/s down E) 0.50 m/s down 12) 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 bottom of the cart. The acceleration of the cart is: A) constant and in the backward direction B) zero C) increasing and in the forward direction D) constant and in the forward direction E) decreasing and in the forward direction 13) A playground merry go round has a radius of 3.0m and a rotational inertia of 600 kg.m 2 . It is initially spinning at 0.80 rad/s when a 20 kg child crawls from the center to the rim. When the child reaches the rim, the angular velocity of the merry go round is: A) 0.73 rad/s B) 0.62 rad/s C) 0.80 rad/s D) 0.89 rad/s E) 1.1 rad/s Final Exam (Section A) Version A‐5 UCSD Physics 2A Winter 2008 Instructor : Vivek Sharma Final Exam (Section A)
14) A picture can be hung on a wall with string in three different ways, as shown. The magnitude of the tension force of the string is: A) least in I B) greatest in I C) greatest in II D) least in III E) greatest in III 15) You were caught on a Caribean pirate ship and are being forced to walk the plank. You are standing at the point marked C. The plank is nailed onto the deck at point A, and rests on the support 0.75m away from A. The center of mass of the uniform plank is located at point B. Your mass is 65 kg and the mass of the plank is 45 kg. What is the minimum downward force the nails must exert on the plank to hold it in place and ensure your survival ? A) 1087 N B) 1087 kg C) 489 N D) 2400 N E) 1911 N 16) A gaseous planet (like Jupiter) suddenly loses part of its mass. A satellite orbiting the planet needs to reduce its orbital radius to 0.80 of the original orbit and needs to slow down to 0.80 of its original speed, in order to remain in orbit. What is the ratio of the planetʹs new mass to the old mass? A) 1.6 B) 2.0 C) 0.64 D) 0.51 E) 0.80 17) The statement: ʺEarth moves in a stable orbit around the Sun and is therefore in equilibriumʺ is A) false, because Earth has considerable acceleration B) false, because no moving body can be in equilibrium C) true, because if it were not in equilibrium then buildings and structures would not be stable D) false, because Earth is rotating and no rotating object can be in equilibrium E) true, because Earth does not fall into or fly away from the Sun Final Exam (Section A) Version A‐6 UCSD Physics 2A Winter 2008 Instructor : Vivek Sharma Final Exam (Section A)
18) What is impossible about the following situation? An object in simple harmonic motion has an equilibrium position x = 0.00 m. At some instant in time, the position of the object is + 3.00 m, the velocity is  2.00 m/s, and the acceleration is + 9.00 m/s2 . A) The speed is less than the displacement. B) The velocity is opposite in direction to the displacement. C) The displacement from equilibrium and the acceleration are in the same direction. D) The acceleration is greater than the speed. E) The numerical value of the velocity is smaller than the distance from the equilibrium position, but the numerical value of the magnitude of the acceleration is larger than the distance from equilibrium. 19) A block of mass m =1.0 kg is supported by two parallel vertical springs with spring constant k 1 = 225 N/m and k2 = 225 N/m. The oscillation frequency of this system is: A) 1.0 Hz B) 8.0 Hz C) 3.4 Hz D) 99.5 Hz E) 0.0 Hz 20) A pendulum that was originally erected by Foucault at the Pantheon in Paris for the Paris Exhibition in 1851 was restored in 1995. It has a 28.0 kg sphere suspended from a 67.0  m light cable. If the amplitude of the swing is 5.00 m, what is the maximum speed of the sphere? A) 3.57 m/s B) 4.16 m/s C) 3.65 m/s D) 1.91 m/s E) 13.1 m/s 21) A meter stick with a mass of 89.5 g is being supported at the 50.0 cm mark by a pivot that is 1.00 cm above the center of mass of the meter stick. The moment of inertia of the stick about that point is 0.00746 kg ·m 2 . What is the period of oscillation of this system? A) 2.01 s B) 5.79 s C) 2.41 s D) 4.02 s E) 2.89 s Final Exam (Section A) Version A‐7 Answer Key Testname: W08A 1) A 2) A 3) C 4) D 5) D 6) A 7) E 8) D 9) C 10) E 11) E 12) B 13) B 14) E 15) D 16) D 17) A 18) C 19) C 20) D 21) B Tear here and submit strip along with the scantron card. Follow TA instructionsName____________________________________________CodeNumber___________________ Final Exam (Section A) Version A‐8 ...
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 Physics, Prof. Vivek Sharma, UCSD Physics 2A, Physics 2A Winter, Vivek Sharma Final

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