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Unformatted text preview: UCSD Physics 2A Fall 2008 Instructor : Vivek Sharma Quiz Seven
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) In the figure above, determine the character of the collision. The masses of the blocks, and the velocities before and after are given. The collision is: A) partially inelastic B) completely inelastic C) perfectly elastic D) characterized by an increase in kinetic energy E) not possible because momentum is not conserved. 2) Two objects of unequal mass are attached to opposite ends of a massless spring. At time t = 0.00 s, the momentum of the first object is p1 and the momentum of the second object is p2 and the magnitude p 1 ≠ p2 . A short time later, the momentum of the first object is - p1 and the momentum of the second object is - p2 . Which statement is necessarily true? A) The average force of the spring on each of the two objects was zero during this time interval. B) The average net external force on the system was zero during this time interval. C) The net external force on the system was always zero during this time interval. D) The net external force on the system was not always zero during this time interval. E) The force of the spring on each of the two objects was always zero during this time interval. 3) Two objects approach each other and collide with no external forces acting on either object. After the collision, the object with mass M has been deflected by 30.0° from its initial direction of travel and the other object with mass 2M has been deflected by 60.0° from its initial direction of travel. What is the deflection of the direction of travel of the center of mass of this two - body system during the collision? A) 50.0° B) 0.00° C) 45.0° D) 40.0° E) The deflection of the center of mass depends on the relative speeds of the two objects before the collision. Name____________________________________________Code-Number___________________ Phys 2A Exam Version A‐1 UCSD Physics 2A Fall 2008 Instructor : Vivek Sharma
4) An observer sees a rocket traveling vertically upward with a speed of 200 m/s. The observer also sees the exhaust gas traveling downward at 100 m/s. If the rate the exhaust gas is leaving the rocket is 2.00 kg/s, what is the force on the rocket from the exhaust gas? A) 400 N upward B) 200 N downward C) 600 N upward D) 100 N upward E) 200 N upward 5) A 920 kg sports car collides into the rear end of a 2300 kg SUV stopped at a red light. The bumpers lock, the brakes are locked, and the two cars skid forward 2.8m before stopping. The police offic er, estimating the coefficient of kinetic friction between tires and road to be 0.80, calculates the speed of the sports car at the time of impact. Assuming the collision occured on a level surface, the speed of the sports car at time of collision was? A) 2.3 m/s B) 9.8 m/s C) 9,2 m/s D) 23 m/s E) 46 m/s 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 springʹs 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) 0.16 m B) 1.6 m C) 0.46 m D) 4.6 m E) 0.9 m 7) A 55 kg bungee jumper leaps from a bridge. She is tied to a bungee cord that is 12m long when unstreched, and falls a total of 31m. What is the maximum acceleration she experiences ? A) 22 m/s 2 upwards B) 22 m/s 2 downwards C) 31 m/s 2 upwards D) 31 m/s 2 downwards E) 16 m/s 2 upwards Phys 2A Exam Version A‐2 UCSD Physics 2A Fall 2008 Instructor : Vivek Sharma 8) As shown in the figure above, a toy race car of mass m is released from rest on the loop - the- loop track. If it is released at a height 2R above the floor, how high is it above the floor when it leaves the track, neglecting friction? A) 1.33 R B) 1.67 R C) 2.00 R D) 1.50 R E) 1.25 R Phys 2A Exam Version A‐3 Quiz 7 Answer Key Q1 Q2 Q3 Q4 Q5 Q6 Q7 Q8 Version A Version B C C D B C D C A B C B D A E A B Version C Version D Version E Version F C A A D C C B A D C B C D E A B E A A A C C C C C E C E B B C E Version G Version H D B A A A B E A D C D A C C B D ...
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