Physics 1A Fall 2013: Quiz 4 Version A 1. Department of Physics Physics 1A Fall Quarter 2013 Dr. Paddock. Version A

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1 Physics 1A Fall 2013: Quiz 4 Version A 1 Department of Physics Physics 1A Fall Quarter 2013 Dr. Paddock Version A DO NOT TURN OVER THIS PAGE UNTIL INSTRUCTED TO DO SO PUT AWAY ALL BOOKS, NOTES, PHONES, COMPUTERS AND STUDY AIDS INSTRUCTION READ ME! 1. ENTER YOUR PID ON YOUR SCANTRON. 2. ENTER THE TEST VERSION IN THE TEST FORM BOX ON YOUR SCANTRON. 3. WRITE YOUR NAME LEGIBLY ON YOUR SCANTRON. 4. Flip over this page when instructed to begin exam. 5. There are 10 problems ranging in difficulty. 6. All answers should be marked on the scantron form WITH PENCIL; no work needs to be shown. 7. An equation sheet is provided on the last page of the exam for reference. 8. Answer all questions. GOOD LUCK!

2 Physics 1A Fall 2013: Quiz 4 Version A 2 Closed book. No work needs to be shown for multiple-choice questions. 1. A red ball strikes an identical blue ball. The blue ball is initially at rest, and the red ball comes to rest after the collision. Which of the following statements is true? a. The momentum of the two ball system increases due to the collision. b. The momentum of the two ball system remains constant in the collision. c. The momentum of the blue ball remains constant in the collision. d. The momentum of the red ball remains constant in the collision. e. The momentum of the red ball increases due to the collision. 2. When two bodies of different masses collide, the impulses they exert on each other are a. equal for all collisions. b. equal but opposite only for elastic collisions. c. equal but opposite only when the bodies have equal but opposite accelerations. d. equal but opposite for all collisions. e. equal but opposite only for inelastic collisions. 3. Lonnie pitches a baseball of mass 0.20 kg. The ball arrives at home plate with a speed of 40 m/s and is batted straight back to Lonnie with a return speed of 60 m/s. If the bat is in contact with the ball for 0.10 s, what is the magnitude of the impulse experienced by the ball? a. 400 N s. b. 360 N s. c. 9.0 N s. d. 240 N s. e. 20 N s. 4. A ball with a mass of 0.25 kg moving at +5.0 m/s makes a head-on collision with a second ball of mass 0.50 kg that is initially at rest. We define the direction of motion of the first ball as the positive x-direction. If the collision is elastic, what is the velocity of the first ball after the collision? a. 2.2 m/s. b. 3.8 m/s. c. 1.7 m/s. d. 2.5 m/s. e. 3.8 m/s.

3 Physics 1A Fall 2013: Quiz 4 Version A 3 5. A bomb, initially at rest, explodes into several pieces. Is linear momentum of the system (the bomb before the explosion, the pieces immediately after the explosion) conserved? Is the kinetic energy conserved? a. both linear momentum and kinetic energy are conserved b. kinetic energy only is conserved c. not enough information d. neither linear momentum nor kinetic energy is conserved e. linear momentum only is conserved 6. A 6.0-kg object moving 2.0 m/s in the positive x direction has a one-dimensional elastic collision with a 4.0-kg object moving 3.0 m/s in the opposite direction. What is the total kinetic energy of the two-mass system after the collision? a. 24 J b. 62 J c. 30 J d. 44 J e. 20 J 7. A 10-g bullet moving m/s strikes and passes through a 2.0-kg block initially at rest, as shown. The bullet emerges from the block with a speed of 400 m/s. To what maximum height will the block rise above its initial position? a. 66 cm b. 46 cm c. 37 cm d. 78 cm e. 56 cm

4 Physics 1A Fall 2013: Quiz 4 Version A 4 8. A 6.0-kg object moving 5.0 m/s collides with and sticks to a 2.0-kg object. After the collision the composite object is moving 2.0 m/s in a direction opposite to the initial direction of motion of the 6.0-kg object. Determine the speed of the 2.0-kg object before the collision. a. 23 m/s b. 11 m/s c. 8.0 m/s d. 15 m/s e. 7.0 m/s 9. The only force acting on a 2.0-kg object moving along the x axis is shown. If the velocity v x is 2.0 m/s at t = 0, what is the velocity at t = 4.0 s? a. 3.0 m/s b. 2.0 m/s c m/s d. 4.0 m/s e m/s

5 Physics 1A Fall 2013: Quiz 4 Version A Three particles are placed in the xy plane. A 40-g particle is located at (3, 4) m, and a 50-g particle is positioned at ( 2, 6) m. Where must a 20-g particle be placed so that the center of mass of this three-particle system is located at the origin? a. ( 1, ) m b. ( 1, 12) m c. ( 1, 2) m d. ( 1, 3) m e. ( 1, 3) m

6 Physics 1A Fall 2013: Quiz 4 Version A 6 Equations and constants: x rcos y rsin ; a avg v t ; v avg x t PE spring 1 k x 2 2 ; r x 2 y 2 y ; tan -1 x v a lim t 0 t ; x v lim t 0 t W F x cos ; v x v ox a x t x 1 v v 2 ox x t x v ox t 1 a t ; 2 2 x v 2 x v ox 2 2a x x 0 f s s F N f k k F N ; F g mg v y v oy a y t y 1 v v 2 oy y t y v oy t 1 a t 2 2 y v 2 y v oy F 0; a = 0 F ma ; F 2on1 F 1on2 2 2a y y ; PE grav mgh; W net W 1 W 2 W 3...; W nc E mec ; E mec KE PE grav PE spring ; P F v W t ; t ; v t r ; a t r ; a C r 2 v 2 t r ; F C m v 2 r ; p mv ; v 1i v 2i v 1f v 2 f ; p i p f ; m 1 v 1i m 2 v 2i m 1 v 1f m 2 v 2 f ; g 9.80 m/s 2 ; 60 min 1 hr; x b 2 rad 1 rev 360 deg cm 1 in; b2 4ac ; 2a 12 in 1 ft ; t ; s r ; I F t p m v f v i ; F p external t ; 100 cm 1 m; 1,000 m 1 km; 60 s = 1 min; 5,280 ft 1 mi ; 1,609 m 1 mi; x x f x i speed avg d ; t KE 1 2 mv2 ; m 1 ft ;