EF 151 Exam #4 - Spring, 016 Page 1 Copy 05 Name: Section: Instructions: Sit in assigned seat; failure to sit in assigned seat results in a 0 for the exam. Put name and section on your exam. Put seating label on your equation sheet. Do not open the test until you are told to do so. On the first page, completely color in the dot for your chosen answers. Write your final answers in the boxes provided If you finish with less than 5 minutes remaining, please stay seated until the exam is over. Stop work immediately when time is over; working after time is over results in an automatic point deduction Turn in your equation sheet with your examination. 11:10 1:40 :10 Pass exams to the aisle; stay seated until all exams are collected. 10 16 17 A10 Rachel B10 Rachel C10 Rachel A16 Connor B16 Connor C16 Connor A17 Tayler B17 Tayler C17 Tayler Guidelines: Assume 3 significant figures for all given numbers unless otherwise stated Show all of your work no work, no credit Include units for all answers and directions for all vectors sphere I mr 5 cylinder 1 I z mr Hollow sphere I mr 3 Hollow cylinder I mr rectangular plate I center 1 1 m h w circular plate I I z x 1 mr 1 I y mr 4
EF 151 Exam #4 - Spring, 016 Page Copy 05 1. ( 3 pts ) Enter your EXAM ID from your seating label. If you don t know your exam ID, enter 000. 0 1 3 4 5 6 7 8 9 Digit #1 Digit # Digit #3 4. ( 1 pt each ) Match each quantity with its correct units. (answers can be used multiple times) N-m kg-m rad rad sec rad sec m m sec m sec kg-m sec Hz Centripetal Acceleration Angular Displacement Angular Velocity Frequency Angular Acceleration Period Torque Mass Moment of Inertia Angular Momentum Rotational Kinetic Energy kg-m sec 14. ( 1 pt ) A disc in the x-y plane is rotating about an axis perpendicular to the x-y plane. What is the direction of its angular momentum vector? y +i i +j j +k k x 15. ( 1 pt each ) Object A is a solid sphere. It is placed on an incline and races the following objects. Predict the winner in each case. Object B Weight Diameter A wins B wins Tie sphere Larger Same sphere Same Smaller Hollow sphere Same Same cylinder Same Same Hollow cylinder Same Same Cart with small wheels Smaller na 1. ( 1 pt each ) A car is speeding up coming toward you while going around a banked turn as shown. Specify the direction for the acceleration components. Center of track Up Down Right Left Up incline Down Incline Out of paper Into paper Centripetal Tangential
EF 151 Exam #4 - Spring, 016 Page 3 Copy 05 3. ( 6 pts ) What is the moment of the 5 lb force about point O? Use CCW as positive. 0.8 ft 4. ( 6 pts ) A flyweel starts from rest. It starts spinning and gains speed at a constant rate for 1.5 seconds. At the end of that time it has made exactly 40 revolutions. What is its angular acceleration?
0.03 m EF 151 Exam #4 - Spring, 016 Page 4 Copy 05 5. ( 6 pts ) Consider two axes perpendicular to the page. If I A = 1.50 g-m and I cm = 0.315 g-m, what is the mass of the book? 0.04m CM A 6. ( 6 pts ) A golf club has a mass moment of inertia of 0.19 kg-m about an axis through point A. If it starts from rest, what is the club s rotational speed after 1.3 seconds if a 13 N-m torque is applied at point A? Point A 7. ( 6 pts ) The small pulley shown below has a speed of 100 rpm. What is the rotational speed in rpm of the large pulley? 6 inch diameter pulley inch diameter pulley
EF 151 Exam #4 - Spring, 016 Page 5 Copy 05 8. ( 1 pts ) We want to balance the object shown at point A by cutting out a hole. At what x,y location should the center of a 15 cm diameter hole be located? Assume uniform thickness and density and all dimensions are in cm. (Hint: use symmetry for one of the values) y 18 30 1 9 A 1 10 13 10 x 9. ( 1 pts ) Prof Schleter (00 lb) rides a Ferris Wheel that is turning at a constant speed of.5 rpm. If the vertical force on him is 14 lb at the location shown, what is the diameter of the wheel? (FBD = KD required) 3 FBD KD
EF 151 Exam #4 - Spring, 016 Page 6 Copy 05 30. ( 1 pts ) A long rod is suspended vertically from a frictionless pin at its upper end. The mass moment of inertia for the rod about the pin is 0.838 kg-m. A 3 gram rubber bullet with a speed of 43 m/s strikes the rod 1.3 m below the pivot point. After the collision, the bullet is travelling backwards at 53 m/s. What is the rotational speed of the rod the instant after the collision? 1.3m 31. ( 1 pts ) Blocks A and B start from rest and are connected by a single rope that goes over a pulley. What is the speed of block A when block B has dropped 3.5 ft? (Hint: use COE) 1 lb A 9 lb, 5 radius solid disk µ k = 0.4 B 6 lb