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quiz5 - UCSD Physics 2A Fall 2008 Instructor Vivek Sharma...

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Unformatted text preview: UCSD Physics 2A Fall 2008 Instructor : Vivek Sharma Quiz Five INSTRUCTIONS:Enter your name and code # in the bottom strip of the first page. Return the entire set of exam sheets with your scantron . Use a #2 pencil to fill your scantron. Write your code number and bubble it in under ““EXAM NUMBER””. Bubble in the quiz version (see letter A--H at bottom of page) in your scantron under ““ EXAM VERSION””. Since Scantron accepts only letter A-D, those with exam versions E-H should enter corresponding letter from A-D in their scantron card. Ask the proctor if you need clarification. MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 1) A dog is standing in the tail bed of a pickup truck. The tail 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 left, as the truck moves to the right, causing the dog to slide towards the back of the truck. B) 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. C) does not move left or right, but simply slides towards the back of the truck. D) moves to the right at the same rate as the truck, so it doesnʹt slide. Figure C 2) A traffic light of weight 100 N is supported by two ropes as shown in Fig. C. What are the tensions in the ropes? A) 50 N B) 66 N C) 56 N D) 63 N E) 83 N 3) A small block of mass m =1kg rests on the sloping side of a triangular block of mass M =5kg as shown below. The angle θ=45o. Assuming all surfaces are frictionless, what is the magnitude of the force F that must be applied to M so that m remains in fixed position relative to M ( that means mass m does not move on the incline) ? A) 49 .0 N B) 58.8 N C) 98.0 N D) 9.8 N E) 41.6 N Name____________________________________________Code-Number___________________ Phys 2A Exam Version A‐1 UCSD Physics 2A Fall 2008 Instructor : Vivek Sharma Figure A 4) A box with weight w = 660 N is on a rough surface, inclined at an angle of 37 degrees. The box is kept from sliding down (in equilibrium) by means of an external force F. The other forces acting on the box are the normal and friction forces, denoted by n and f. A force diagram, showing the four forces which act on the box, is shown in Figure A. The magnitude of f is 250 N. The external force F is removed and the box accelerates. The magnitudes of the other forces are unchanged. The acceleration of the box is closest to: A) 0.60 m/s2 B) 2.2 m/s2 C) 3.1 m/s2 D) 1.2 m/s2 E) 4.1 m/s2 5) Consider what happens when you jump up in the air. Which of the following is the most accurate statement? A) Since the ground is stationary, it cannot exert the upward force necessary to propel you into the air. Instead, it is the internal forces of your muscles acting on your body itself which propels the body into the air. B) You are able to spring up because the earth exerts a force upward on you which is stronger than the downward force you exert on the earth. C) When you push down on the earth with a force greater than your weight, the earth will push back with the same magnitude force and thus propel you into the air. D) It is the upward force exerted by the ground that pushes you up, but this force can never exceed your weight. E) When you jump up the earth exerts a force F1 on you and you exert a force F2 on the earth. You go up because F1 > F2 , and this is so because F1 is to F2 as the earthʹs mass is to your mass. 6) A block is on a frictionless table, on earth. The block accelerates at 9.7 m/s2 when a 30 N horizontal force is applied to it. The block and table are set up on the moon. The acceleration due to gravity at the surface of the moon is 1.62 m/s2 . A horizontal force of 15 N is applied to the block when it is on the moon. The acceleration imparted to the block is closest to: A) 5.3 m/s2 B) 5.8 m/s2 C) 4.9 m/s2 D) 6.3 m/s2 E) 4.4 m/s2 7) Three books (X, Y, and Z) rest on a table. The weight of each book is indicated. The force of book Z on book Y is: A) 9 N B) 14 N C) 19 N D) 5 N E) 0 N Phys 2A Exam Version A‐2 UCSD Physics 2A Fall 2008 Instructor : Vivek Sharma 8) A jet aircraft is accelerating at 3.8m/s2 as it climbs at an angle of 18 o above the horizontal as shown in the figure below. What is the magnitude of the force that the cockpitʹs seat exerts on the pilot of mass 75.0 kg? A) 271 N B) 867 N C) 823 N D) 435 N E) 285 N Phys 2A Exam Version A‐3 Quiz 5 Answer Key Q1 Q2 Q3 Q4 Q5 Q6 Q7 Q8 Version A Version B C E E B B C C A B B A A D A C C Version C Version D Version E Version F D B C C C C E E D E D D A E B D D A B C E A E D A C D C A B D D Version G Version H A D C D E A E D E D E D A C B E ...
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