Position versus Time Graphs Conceptual Question| University Physics

Problem:

The motions described in each of the questions take place at an intersection on a two-lane road with a stop sign in each direction. For each motion, select the correct position versus time graph. For all of the motions, the stop sign is at the position x=0, and east is the positive x-direction.

The figure shows six graphs, labeled A to Feach of which shows the position as a function of time. Time is measured on the positive x-axis and the position is measured on the y-axis. On graph A the position decreases linearly from the point, which lies on the positive y-axis, intersecting the positive x-axis. On graph B the position increases linearly from the origin. On graph C the position smoothly increases from the origin, forming a concave curve and reaching a constant value. On graph D the position increases linearly from the point, which lies on the negative y-axisintersecting the positive x-axis. On graph E the position smoothly increases from the origin, forming a convex curve. On graph F the position smoothly decreases from the point, which lies on the positive y-axis, to zeroforming a convex curve.

PART A. A driver ignores the stop sign and continues driving east at constant speed.

ANSWER: D

PART B. A driver ignores the stop sign and continues driving west at constant speed.

ANSWER: A

PART C. A driver, traveling west, slows and stops at the stop sign.

ANSWER: F

PART D. A driver, after stopping at the stop sign, travels east with a positive acceleration.

ANSWER: E

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