Unformatted text preview: UCSD Physics 2A Fall 2009 Instructor : Vivek Sharma Quiz Three
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--D at bottom of page) in your scantron under ““ EXAM VERSION””.
MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. Figure A 1) Deja vu all over again ! In Figure A, suppose the situation sketched. Once in a circus in rainy Hamburg, I saw a stunt in which clown fired out of a cannon landed in a speeding toy fire engine which was racing away from him. The clown, of mass 60 kg, is fired with speed νo at the same instant the fire engine starts to move directly away from him. The fire engine moves forward with a constant acceleration of g/4. The fire engine is 5 meters ahead of the clown when they start. Assume the clown lands at the same elevation from which he is fired. The cannon makes an angle Θ with horizontal, where sinΘ = 4/5 and cosΘ = 3/5. With what speed must the clown leave the cannon in order to land in the truck? A) 4.43 m/s B) 4.85 m/s C) 2.15 m/s D) 6.50 m/s E) 8.75 m/s 2) 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 right, but not as quickly as the truck is moving to the right, causing it to slide towards the back of the truck. B) does not move left or right, but simply slides towards the back of the truck. C) moves to the right at the same rate as the truck, so it doesnʹt slide. D) moves to the left, as the truck moves to the right, causing the dog to slide towards the back of the truck. Enter Your name and Code number Name____________________________________________Code-Number___________________ Exam Version A‐1 UCSD Physics 2A Fall 2009 Instructor : Vivek Sharma
3) Consider what happens when you jump up in the air. Which of the following is the most accurate statement? A) 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. B) It is the upward force exerted by the ground that pushes you up, but this force can never exceed your weight. C) 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. D) 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. E) 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. 4) A block is on a frictionless table, on earth. The block accelerates at 9.7 m/s 2 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/s 2 . 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) 6.3 m/s 2 B) 4.9 m/s 2 C) 5.3 m/s 2 D) 5.8 m/s 2 E) 4.4 m/s 2 5) A 5 kg block is suspended by a rope from the ceiling of an elevator as the elevator accelerates downward at 3.0 m/s2 . The tension force of the rope on the block is: A) 34 N up B) 15 N up C) 34 N down D) 64 N down E) 64 N up 6) 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) 19 N B) 0 N C) 14 N D) 5 N E) 9 N 7) A crate rests on a horizontal surface and a woman pulls on it with a 10 N force. Rank the situations shown below according to the magnitude of the normal force exerted by the surface on the crate, least to greatest A) 1,2,3 B) 3,2,1 C) 2,1,3 D) 1,3,2 E) 3,1,2, Test Version A‐2 UCSD Physics 2A Fall 2009 Instructor : Vivek Sharma
8) Three blocks (A,B,C), each having mass M, are connected by strings as shown. Block C is pulled to the right by a force F that causes the entire system to accelerate. Neglecting friction, the net force acting on block B is: A) F /3 B) 0 C) F D) 3 F /2 E) 2 F /3 Test Version A‐3 Version Q1 Q2 Q3 Q4 Q5 Q6 Q7 Q8 A E B A B A E B A B C A E B B B E D Quiz 3 Answer Key C D E C C A C E B A A E C B B A C C E C C A A A B B B F A B A A D B E A G E D D A C D E D H C C A D C C B E ...
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