02homework02

# 02homework02 - Husain Zeena Homework 2 Due Sep 9 2003 4:00...

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Husain, Zeena – Homework 2 – Due: Sep 9 2003, 4:00 am – Inst: H L Berk 1 This print-out should have 23 questions, check that it is complete. Multiple-choice questions may continue on the next column or page: fnd all choices beFore making your selection. The due time is Central time. Please work through each problem. 001 (part 1 oF 1) 10 points The graph below shows the velocity v as a Function oF time t For an object moving in a straight line. t O v Which oF the Following graphs shows the corresponding displacement x as a Function oF time t For the same time interval? 1. t O x 2. t O x 3. t O x correct 4. t O x 5. t O x Explanation: The displacement is the integral oF the ve- locity with respect to time ~x = Z ~v dt . Because the velocity increases linearly From zero at frst, then remains constant, then de- creases linearly to zero, the displacement will increase at frst proportional to time squared, then increase linearly, and then increase pro- portional to negative time squared. ±rom these Facts, we can obtain the correct answer. 002 (part 1 oF 1) 10 points An object was suspended in a fxed place ( y = 0) and then allowed to drop in a Free Fall. Taking up as the positive vertical direction, which oF the Following graphs correctly repre- sents its vertical motion as displacement vs time ? 1. t y 2. t y 3. t y 4. t y 5. t y

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Husain, Zeena – Homework 2 – Due: Sep 9 2003, 4:00 am – Inst: H L Berk 2 6. t y 7. t y 8. t y 9. t y correct 10. t y Explanation: The object is undergoing a constant down- ward gravitational acceleration g . The slope of a position vs time curve represents the velocity. Given g 6 = 0 m / s 2 a < 0 m / s 2 a = - g m / s 2 v 0 = 0 m / s y 0 = 0 m . Since y = y 0 + v 0 t + 1 2 a t 2 , therefore y = - 1 2 g t 2 . This is a parabolic shaped curve starting a y = 0 with a continuously decreasing slope as time increases. Only the Fgure below is correct. t y 003 (part 1 of 2) 10 points A person travels by car from one city to an- other. She drives for 38 . 3 min at 75 . 8 km / h, 14 . 6 min at 93 . 5 km / h, 42 . 3 min at 47 . 9 km / h, and spends 16 . 7 min along the way eating lunch and buying gas. Determine the distance between the cities along this route. Correct answer: 104 . 907 km. Explanation: Distances traveled are x 1 = v 1 t 1 x 2 = v 2 t 2 x 3 = v 3 t 3 Then the total distance traveled is x = x 1 + x 2 + x 3 = (48 . 3857 km) + (22 . 7517 km) + (33 . 7695 km) = 104 . 907 km . 004 (part 2 of 2) 10 points Determine the average speed for the trip. Correct answer: 56 . 2503 km / h. Explanation: And, time spent is t = t 1 + t 2 + t 3 + t other = (38 . 3 min) + (14 . 6 min) + (42 . 3 min) + (16 . 7 min) = 1 . 865 h . Hence v av = x t = 104 . 907 km 1 . 865 h = 56 . 2503 km / h .
Husain, Zeena – Homework 2 – Due: Sep 9 2003, 4:00 am – Inst: H L Berk 3 005 (part 1 of 1) 10 points A mass attached to a spring oscillates back and forth as indicated in the position vs. time plot below. P

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02homework02 - Husain Zeena Homework 2 Due Sep 9 2003 4:00...

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