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Unformatted text preview: MasteringPhysics: Assignment Print View 1 of 14 10/4/2007 3:41 PM [ Print View ] PHCC 141: Physics for Scientists and Engineers I - Fall 2007 3a. Motion in Two or Three Dimensions Due at 11:59pm on Friday, September 7, 2007 Hide Grading Details Number of answer attempts per question is: 5 You gain credit for: correctly answering a question in a Part, or correctly answering a question in a Hint. You lose credit for: exhausting all attempts or requesting the answer to a question in a Part or Hint, or incorrectly answering a question in a Part. Late submissions: reduce your score by 100% over each day late. Hints are helpful clues or simpler questions that guide you to the answer. Hints are not available for all questions. There is no penalty for leaving questions in Hints unanswered. Grading of Incorrect Answers For Multiple-Choice or True/False questions, you lose 100% / ( # of options - 1 ) credit per incorrect answer. For any other question, you lose 3% credit per incorrect answer. Standard kinematic definitions, two body problems Position, Velocity, and Acceleration Learning Goal: To identify situations when position, velocity, and /or acceleration change, realizing that change can be in direction or magnitude. If an object's position is described by a function of time, (measured from a nonaccelerating reference frame), then the object's velocity is described by the time derivative of the position, , and the object's acceleration is described by the time derivative of the velocity, . It is often convenient to discuss the average of the latter two quantities between times and : and . Part A You throw a ball. Air resistance on the ball is negligible. Which of the following functions change with time as the ball flies through the air? Hint A.1 Newton's 2nd Law Hint not displayed ANSWER: only the position of the ball only the velocity of the ball only the acceleration of the ball the position and velocity of the ball the position and the velocity and acceleration of the ball Part B You are driving a car at 65 mph. You are traveling north along a straight highway. What could you do to give the car a nonzero acceleration? Hint B.1 What constitutes a nonzero acceleration? Hint not displayed ANSWER: Press the brake pedal. MasteringPhysics: Assignment Print View 2 of 14 10/4/2007 3:41 PM Turn the steering wheel. Either press the gas or the brake pedal. Either press the gas or the brake pedal or turn the steering wheel. Part C A ball is lodged in a hole in the floor near the outside edge of a merry-go-round that is turning at constant speed. Which kinematic variable or variables change with time, assuming that the position is measured from an origin at the center of the merry-go-round?...
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