University of Texas COS 32 assignment 3- solutions roman (amr4824) – assignment 3

roman (amr4824) – assignment 3 – shih – (58595) 1 This print-out should have 25 questions. Multiple-choicequestionsmay continueon the nextcolumn or page – find allchoices before answering. extra office hours in RLM 2.216 on thursday 09/20, 8-10pm 001 10.0 points Which object has the greatest inertia? 1. An ocean liner correct 2. A car 3. A mosquito 4. A VW bug Explanation: A body’s inertia is a measure of its resistance to changes in motion, or acceleration. The ocean liner has the most inertia since it has the most mass, and it would be the most difficult to accelerate. 002 10.0 points Two men decide to use their cars to pull a truck stuck in mud.They attach ropes and one pulls with a force of712 N at an angle of 32◦ with respect to the direction in which the truck is headed, while the other car pulls with a force of 1178 N at an angle of 23 ◦ with respect to the same direction. 712 N 32 ◦ 1178 N 23 ◦ What is the net forward force exerted on the truck in the direction it is headed? Correct answer:1688.16 N. Explanation: Let : F1 = 712 N , F2 = 1178 N , θ1 = 32◦ , and θ2 = 23◦ . For the first vehicle, the forward component is F1f = F1 cos θ1 = (712 N) cos 32 ◦ = 603.81 N . Similarly, for the second vehicle, F2f = F2cos θ2 = (1178 N) cos 23 ◦ = 1084.35 N . Thus the net forward force on the truck is Ff = F1f + F2f = 603.81 N + 1084.35 N = 1688.16 N . 003 (part 1 of 3) 10.0 points Consider a coin which is tossed straight up into the air. After it is released itmoves upward,reachesits highestpoint and falls back down again. Air resistance can be neglected. What force acts on the coin while it moves upward after it is released? 1. A force acting down and constant. correct 2. A force acting down and increasing. 3. A force acting down and decreasing. 4. A force acting up and increasing. 5. A force of zero. 6