Exam 6 Key - Part 1: Circle the correct answer. Each is...

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Unformatted text preview: Part 1: Circle the correct answer. Each is worth 5 points. 1. Two cars of the same mass start at the same speed. Car A undergoes a dramatic crash with several bounces, some spinning and a little rolling. Car B simply hits a wall head on. Both stop completely. Which car experiences the greater average force? ' / ""T'Hx Car A LCaLB/X) Both are the same 2. Which car from #1 experiences the greater magnitude of impulse? __—-—-——._.‘ “\‘K fad-'— Car A Car B (goth are the same“ ,i' _____H_ .\ /' KH____________,_... 3. I am holding a bowling ball close to my chest. lfl straighten my arms but keep the ball at the same height, what do I have to do to keep my center of gravity in the same place as before? cm L M v e A. Lean forwards. CB) Lean backwards. C. Nothing. 4. I drop a bowling ball from 1.0 m above a concrete floor, and it bounces to a height of 0.13 m. The bowling ball’s collision with the floor is elastic in physics TRUE FALSE\ 5. A puppy jumps into my lap while I’m in an office chair, and we start to roll. If terms. the system is “the puppy, me, and the chair,” which of the following quantities is definitely not conserved? "Mechanical Energy. . Momentum. C. Cuteness. 6. Which is faster? A. 33.3 revolutions per minute @500 radians per second .I. J 1 7. The centripetal force required-to make a 1.0 kg mass go in a 1.0 m radius circle at 1.0 m/s is 1.0 N. Ifa string is used to try to do this, but the tension in the string is 1.5 N, what happens? @The mass moves to a smaller radius. B. The mass moves to a larger radius. 'C. The tangential component of velocity increases. D. The tangential component of velocity decreases. 8. If I doubled the mass of ‘the Earth and the radius of the Earth, the acceleration of gravity on the surface would stay the same. TRUE 9. “Choking up” on a baseball bat by holding it farther from‘the end lets y0u sWing it faster because the moment of inertia of the bat is madehrlarger. TRUE (132,89 10. Dr. Van Domelen and Wes Erbsen (the recitation TA) want to balance on a see-saw (a plank attached to a pivot in its middle). Which of us needs to sit closer to the center? Van Domelen . Wes Erbsen C. We should both sit the same distance from the center. Part 2: 10 points each for the correct answers. 1 1. In general, moment of inertia is BMRZ. We have an object with a mass of 0.65kg and a radius of 0.34m. If a force of 25N applied perpendicular to the radius gives it an angular acceleration of 166 rad/s2, what is B? _ T'x. _ . 12. I’m sliding along ice (very low friction) at 1.1 m/s and mass 122 kg including my heavy bag of canned food (I’m 89 kg without it). How fast to I have to throw the bag (with respect to the ice) in order to come to a stop? W /‘ v. I W“ Vru ? 1E: v31 V10:V»o 311% m , 56021}, 015+»:an :ijfl “avg. W 3 0 MC» Minx—)2} be _ flfl \ffifff 5U My??ij : a; * m4] w /r-*’:‘%\ a $0 3 Wig/3' Part 3: Show all work. 13. A projectile that weighs 2.8 N has a vector momentum of 25 kg m/s at 340 above the horizontal at to = 0.0s. What is the magnitude of its momentum at t] = 3.2 s? Assume it doesn’t hit anything or land on the ground before t]. A. (5 points) Define all your variables, B. (5 points) Draw a diagram both the known values and the unknowns of what’s going on, and label you’ll need to solve for. «ER it with your variables r70 .2 525' L”) ’7) Pa K") (not with numbers). :siw/ (4?) 1" UtU§ C. (15 points) Show your work solving the problem. If you use the back of the _ _ _ sheet, please m e grader knows to look there. \ - {PM AP»: $330.4 ’9 "’b ..__ 167’ 5 M . \ D- (5 points) Answer: j ...
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Exam 6 Key - Part 1: Circle the correct answer. Each is...

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