PHYS 1110 Exam 3 NAME:______________________________ Spring 2006 E3.1 Third Midterm Student ID #__________________________________________________ Section number and/or TA Name:___________________________________ Please do not open the exam until you are asked to. • Your exam should have 7 pages, numbered E3.1 thru E3.7. • This exam consists of 15 multiple choice questions, worth 5 points each, and a long-answer problem worth 25 points, for a total of 100 points. • Write your answers in the space provided on each page for the written question. Use the back of the page if needed. Circle the correct letter for the multiple choice questions. SHOW YOUR WORK ON THE WRITTEN QUESTIONS. Full credit will be given only for the correct answer accompanied by your reasoning. PLEASE!! 1. Print your name on each page in the space provided. 2. Print your student Identification Number on the page above. 3. Bubble your name and ID on the bubble sheet provided. 4. Write the name of your TA neatly in the big blank space at the bottom of the bubble sheet. Our TA's names are Scott Barbarow, Eszter Horanyi, Jason Pawlowski, Mike Shefferstein, Aaron Svoboda and Chandra Turpen. I recommend: Don’t waste time erasing on the written problems. Just put a line through defective reasoning. Ask for more paper if needed. At the end of the exam, check that you have completed all the questions. By handing in this exam, you agree to the following statement: "On my honor, as a University of Colorado Student, I have neither given nor received unauthorized assistance on this work" Signature______________________________________________ Possibly useful information: On any problems involving gravity, use g=10 m/s2! Also, Rearth= 6.4×106 m, radius of moon’s orbit=3.9×108 m Mass of the Earth is 24610kg×As always, neglect friction or air resistance (unless otherwise clearly stated) Good luck!PHYS 1110 Exam 3 NAME:______________________________ Spring 2006 E3.2 Third Midterm Circle the closest answer and Bubble in questions 1-15 ON YOUR BUBBLE SHEET! 1. An idiot drops a water balloon from the top of a building onto the head of a victim standing on the sidewalk below. The balloon is traveling at the painful speed of 32 m/s when it hits the victim. Assuming the balloon started with zero initial velocity, from what height did it fall? A) 1.6 m. B) 102 m. C) 51 m. D) 32 m. 2. A massless spring hangs from the ceiling. It has an equilibrium length of 30 cm. A mass is hung from the spring and the spring stretches to a new length of 50 cm. What is the change in the potential energy of the spring if its spring constant is 2000 N/m? A) 90 J B) 250 J C) 40 J D) 400 J 3. A particle moving in 1D experiences a conservative force given by F=α−βx3. Assuming that the zero of potential energy occurs at x= 0, find the potential field the particle is in. A) U(x) =αx −βx4/4 B) U(x) =−αx +βx4/4 C) U(x) = 3βx2 D) U(x) =−3βx3 4. An object of mass moves without friction on a straight track with a speed of 3 m/s in the positive direction. It collides with a second object of the same mass that is initially moving in the negative direction with a speed of 6 m/s. If the objects collide elastically, what is the speed and direction of the second mass after they collide? m A) +6 m/s B) -6 m/s C) +3 m/s D) -3 m/sPHYS 1110 Exam 3 NAME:______________________________ Spring 2006 E3.3 Third Midterm 5. A traveler pulls a trunk on a level floor with a strap which makes an angle of with respect to the floor. If 413 J of work are done as the trunk is moved a distance of 15 m, what is the tension on the strap? 36o A) 5012 N B) 68 N C) 22 N D) 34 N 6. In a 1D system, there is a force given by F(x)=bx3. How much work is done by this force in moving an object from x= 0 m to x= 2 m if b=4 N/m? A) 16 J B) 64 J C) 4 J D) 30 J 7. A satellite orbits the earth 3 times per day. What is the radius of its orbit, assuming it to be circular? (You may ignore the effect of the moon.) A) m 0.47 × 107B) 6 m .15 × 107C) 2 m .05 × 107D) m 2.11 × 106 8. A yoyo, which can be considered as a uniform disc of radius 4 cm with a mass of 50 gm, “sleeps” while the string suspending it is fully extended. The string and yoyo, originally at rest apart from the yoyo’s rotational motion, are accelerated straight up at a rate of 50 cm/s . What is the change in the angular momentum of the yoyo during the vertical acceleration? Friction due to the string can be ignored. 2 A) 15.1 kg m /s 2B) -15.1 kg m /s 2C) 30.2 kg m /s 2D) No changePHYS 1110 Exam 3 NAME:______________________________ Spring 2006 E3.4 Third Midterm 9. A meteroid heading straight toward the earth’s center has a speed of 15.3 km/s as it crosses the moon’s orbit (which you may assume is circular). What is its speed when it hits the earth? A) 28.8 km/s B) 87.4 km/s C) 19.0 km/s D) 18.9 km/s 10. The plot below shows the potential energy of a particle which depends on r, the distance from the origin. For which of the regions indicated on the plot can the force exerted on the particle be equal to zero? r U(r) A B C D A) region A B) region B C) region C D) regions B and D E) regions A and D 11. What is the ratio of the escape velocity of a rocket launched from sea level to one launched from the summit of Chomolungma which has an elevation of 8850 m, vSEA/vCHOMO? A) 1.0014 B) 0.9986 C) 1.0007 D) 0.9993 12. A bicycle wheel has a total mass of 4 kg, and a radius of 0.5 m. What is the moment of inertia, I, for this wheel? A) 2 kg.m2B) 1 kg.m2C) 0.5 kg.m2D) 0.4 kg.m2PHYS 1110 Exam 3 NAME:______________________________ Spring 2006 E3.5 Third Midterm 13. A pendulum consisting of a massless rod 1 m in length with one end attached to a frictionless pivot. A 1 kg mass is attached to the other end. The pendulum is mounted near the rim of a Merry-Go-Round with a radius R= 5 m which rotates at a constant angular speed of ω=1 rad/s. The pendulum makes an angle θ with respect to the vertical when the pendulum in equilibrium and at rest with respect to the Merry-Go-Round with the weight exactly above its rim. Which is a true statement for θ? r ω pendulum θ R A) sinθ=1/2 B) cosθ=1/2 C) tanθ=1/2 D) θ=1/2 rad 14. A solid uniform sphere of radius, R, and a hoop of the same radius are rolled without slipping down an inclined plane of height H. Which reaches the
View Full Document
Unlocking...