EF 151 Final Exam - Spring, 2017 Page 3 Copy 223 Name: Section: 1. Enter your EXAM ID from your seating label. If you don t know your exam ID, enter 000. 0 1 2 3 4 5 6 7 8 9 Digit #1 Digit #2 Digit #3 4. (1 pt) The area under a V-T curve gives the following information: Change in position Change in velocity Change in acceleration 5. (1 pt) Which of these is NOT a vector quantity? Speed Velocity Acceleration Displacement 6. (1 pt) The net force on a moving object suddenly becomes zero. The object then: stops during a continues at stops abruptly changes direction short time interval constant velocity slows down gradually 7. (1 pt) A 2400 lb car is parked on a 12 slope. The magnitude of the friction force is? 0 2400lb(sin(12 )) 2400lb(cos(12 )) 2400lb cannot determine 8. (1 pt) Which is an example of a conservative force? Friction Spring force Air resistance Heat 9. (1 pt) What is NOT an acceptable unit for impulse? 10. (1 pt) The mass moment of inertia of the object shown about the center of mass (CM) is 0.4 kg m 2. The mass moment of inertia about point A is: < 0.4 kg-m 2 = 0.4 kg-m 2 > 0.4 kg-m 2 cannot determine A CM
EF 151 Final Exam - Spring, 2017 Page 4 Copy 223 11. (1 pt) A go kart travels around a circular track at a constant speed. Which of these statements is true? The go-kart has constant velocity The go-kart has zero acceleration Both (a) and (b) are true Neither (a) or (b) is true 12. (3 pts) Michael drops a ball off the roof of Perkins, which is 45 feet above the ground. At what time is the ball 6 feet above the ground? 13. (3 pts) A particle starts at the origin and has an initial velocity of 6 3 m/s, and an acceleration of 3 7 m/s 2. If the particle has a final position of 10 4 m, what is the particle s final y velocity? 14. (3 pts) The TREC basketball courts have a floor area of 92 feet by 45 meters. What is the area of the TREC basketball courts in the units of square horse lengths? 1 meter = 3.28 feet 1 horse length = 96 inches 15. (3 pts) An 80 kg person is on an amusement park ride that is accelerating straight up at 6 m/s 2. Determine the normal force on the person.
EF 151 Final Exam - Spring, 2017 Page 5 Copy 223 16. (3 pts) Determine the minimum force P to keep the block from moving. P 18 lb 15 lb μ s = 0.8, μ k = 0.7 17. (3 pts) Mike is walking at 4.6 ft/s on a moving sidewalk that is going at +3.2 ft/s (don t ask why Mike is walking backwards). Lisa is walking beside the moving sidewalk at +4.1 ft/s. Determine the relative velocity of Mike with respect to Lisa. 18. (3 pts) An object has a non constant force applied over a period of 13 seconds, as shown in the figure. If the object starts at 3 ft/s and ends at 19 ft/s after 13 sec, what is the mass of the object? F 10 lb 13 sec x 19. (3 pts) A system has an efficiency of 37% and is designed for a total power of 77 kw. How much useful work is done in 30 seconds?
EF 151 Final Exam - Spring, 2017 Page 6 Copy 223 20. (3 pts) A Nerf dart (1.3 grams) is launched at a velocity of +44 m/s toward a stationary plastic target (37 grams). The dart collides and sticks to the target. What is the velocity of the plastic target after the collision? 21. (3 pts) Determine the x coordinate of the center of mass. 22. (3 pts) Determine the torque of the 38 lb force about point O. 4 ft y 38 lb 20 O 3 ft x 23. (3 pts) A merry go round has a mass moment of inertia of 50 kg m 2 and a 30 kg child is riding the merry go round at 1.1 m from the center. The merry go round is spinning at 4 rad/s. The child moves towards the center so the child is now at 0.6 m from the center. Determine the new angular speed of the merry go round.
EF 151 Final Exam - Spring, 2017 Page 7 Copy 223 24. (7 pts) Dr. Bennett starts from Perkins and goes for a walk on campus. First, he walks 585 ft North, then walks 600 ft 50 o S of E and then walks 545 ft 30 o S of W. How far and in what direction does Dr. Bennett need to walk to get back to where he started? 25. (7 pts) Dr. McCord drives her Prius down the road at a constant acceleration of 0.8 ft/s 2. If she drives for 45 s and has an average speed of 77 ft/s over the total trip, what was her initial speed?
EF 151 Final Exam - Spring, 2017 Page 8 Copy 223 26. (7 pts) Determine the magnitude and acceleration of the cart. A complete FBD = KD is required. 80 N 24 30 kg 18 27. (7 pts) A projectile is launched as shown and hits the ground 1.6 seconds later. Determine the magnitude of the initial velocity. 8 ft 60 ft
EF 151 Final Exam - Spring, 2017 Page 9 Copy 223 28. (7 pts) A puck launcher launches a 12 gram puck so that it slides on a flat table. The spring (k = 175 N/m) is initially pulled back 3 cm. Once released, the puck travels 87 cm, where the velocity of the puck is measured to be 0.6 m/s. What is the coefficient of friction between the puck and the table? 29. (7 pts) Cart A (127 kg) is traveling at +22 m/s when it collides with cart B (207 kg) traveling at 3 m/s. After the collision, Cart A is traveling +4 m/s. What is the coefficient of restitution for the collision?
EF 151 Final Exam - Spring, 2017 Page 10 Copy 223 30. (7 pts) A 2000 lb car is going around a flat 250 ft radius curve. The car is traveling at 45 ft/s and slowing down at a rate of 12 ft/s 2. Determine the magnitude of the total friction force. A complete FBD=KD is required. 31. (7 pts) A cylinder is rolling at a speed of 3.8 m/s. Determine how far up the hill, d, the cylinder will roll. The mass moment of inertia of a cylinder is. 26