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Unformatted text preview: Answers for Quiz 6
A 1) D 2) A 3) A 4) B 5) C 6) C 7) A B 1) A 2) D 3) D 4) C 5) E 6) B 7) A C 1) E 2) D 3) D 4) A 5) C 6) D 7) A D 1) C 2) A 3) B 4) E 5) C 6) C 7) D E 1) E 2) A 3) A 4) B 5) C 6) E 7) A F 1) C 2) A 3) C 4) B 5) C 6) A 7) C G 1) B 2) A 3) E 4) C 5) E 6) E 7) C H 1) A 2) E 3) A 4) B 5) B 6) A 7) D I 1) E 2) B 3) B 4) C 5) C 6) C 7) A J 1) E 2) B 3) D 4) D 5) C 6) D 7) C K 1) E 2) B 3) A 4) A 5) D 6) D 7) D L 1) C 2) B 3) D 4) B 5) B 6) A 7) A UCSD Physics 2A Winter 2008 Instructor : Vivek Sharma Quiz Seven
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 quiz version (see letter A--L at bottom of page) in your scantron under ""TEST VERSION"". Since Scantron accepts only letter A-D, those with exam versions E-H or I-L 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 person wants to make herself independent from commercial electrical energy providers. She builds an electrical generator for her home that works by attaching a 24.0-kg mass to a chain which turns a generator as gravity pulls the mass to the floor a distance of 2.00 m. Assuming the system to be 100% efficient, how many times in one hour would the mass need to picked up and attached to the chain so gravity could do the work needed to power a 100-W lightbulb for one hour? A) 125 B) 7.50 103 C) 247 D) 764 E) 463 2) A man pulls a 100-N crate up a frictionless 30. slope 5m high, as shown. Assuming that the crate moves at constant speed, the work done by the man is: A) 500 J B) -500 J C) 0 J D) 1000 J E) -250 J 3) A mother travelling in a car buckles herself in with a seat belt and holds her 18 kg toddler on her lap. Use Work-energy principle to answer the following question. If the car, moving with speed of 25m/s in an accident and is brought to stop over a distance of 12m. How much force will the parent need to exert on the child? A) 470 N B) 940 N C) 19 N D) 235 N E) 176 N --------Tear here and submit strip along with the scantron card. Follow TA instructions------Name____________________________________________Code-Number___________________ Phys 2A Quiz Seven Test Version A1 UCSD Physics 2A Winter 2008 Instructor : Vivek Sharma
4) In a truck-loading station at a post office, a small 0.200 kg package is released from rest at point A on a track that is one quarter of a circle with radius 1.60m as shown in the figure above. The size of the package is much smaller than 1.60m so the package can be treated as a particle. It slides down the track and reaches point B with a speed of 4.80m/s. From point B, it slides on a level surface a distance of 3.0m to point C, where it comes to rest. What is the coefficient of kinetic friction on the horizontal surface? A) 0.784 B) 0.392 C) 0.0784 D) 1.392 5) Jane jumps off a bridge with a bungee cord tied around her ankle. She falls for 15m before the elastic bungee cord begins to stretch. Janes mass is 75kg and the spring constant of the bungee cord is 50N/m. How far below the bridge will Janes foot be before coming to a stop. Ignore the mass of the cord and neglect the air resistance. A) 4m B) 30m C) 55m D) 70m E) 110m Phys 2A Quiz Seven Test Version A2 UCSD Physics 2A Winter 2008 Instructor : Vivek Sharma
6) In the figure below, a 3.5 kg block is accelerated from rest by a compressed spring of spring constant 640N/m. The block leaves the spring at the springs relaxed length and then travels over a horizontal floor with a coefficient of kinetic friction of 0.25. The friction force stops the block in a distance D = 780 cm. What was the original compression distance of the spring? A) 1.6 m B) 4.6 m 7) C) 0.46 m D) 0.9 m E) 0.16 m You and your bicycle have combined mass 80.0kg. When you reach the base of a bridge, you are travelling along the road at 5.0m/s . At the top pf the bridge (see figure above), you have climbed a vertical distance of 5.20m and have slowed to 1.50m/s. You can ignore work done by friction and any inefficiency in the bike or your legs. How much work have you done with the force you apply to the pedals? A) +3170 J B) -4987 J C) +4987 J D) -3167 J E) -3170 J Phys 2A Quiz Seven Test Version A3 Answer Key Testname: Q7 1) 2) 3) 4) 5) 6) 7) D A A B C C A --------Tear here and submit strip along with the scantron card. Follow TA instructions------Name____________________________________________Code-Number___________________ Phys 2A Quiz Seven Test Version A4 ...
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