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Ch 02: Motion Along a Straight Line
Young & Freedman Calc - University Physics 15th Edition
Young & Freedman Calc15th EditionUniversity PhysicsISBN: 9780135159552Not the one you use?Change textbook
Chapter 2, Problem 10b

A physics professor leaves her house and walks along the sidewalk toward campus. After 55 min, it starts to rain, and she returns home. Her distance from her house as a function of time is shown in Fig. E2.102.10. At which of the labeled points is her velocity constant and positive?
Position-time graph showing a curve with labeled points I to V; velocity is zero at point IV.

Verified step by step guidance
1
To determine where the velocity is constant and positive, we need to look for sections of the graph where the distance from the house increases linearly with time.
Velocity is the rate of change of distance with respect to time. A constant velocity implies a straight line on a distance-time graph.
A positive velocity means the slope of the line is positive, indicating that the distance from the house is increasing.
Examine the graph and identify the segments where the line is straight and has a positive slope. These segments indicate constant positive velocity.
In the provided graph, the segment from point 'a' to point 'b' is a straight line with a positive slope, indicating that the velocity is constant and positive in this interval.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Velocity

Velocity is a vector quantity that refers to the rate at which an object changes its position. It is defined as the displacement per unit time and has both magnitude and direction. In the context of a position-time graph, the slope of the line represents the velocity. A positive slope indicates positive velocity, meaning the object is moving away from the starting point.
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Position-Time Graph

A position-time graph displays an object's position relative to time. The x-axis typically represents time, while the y-axis represents position. The slope of the graph at any point indicates the object's velocity. A straight line indicates constant velocity, while a curved line suggests changing velocity. In this graph, segments with a constant slope indicate constant velocity.
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Constant Velocity

Constant velocity occurs when an object moves at a steady speed in a straight line, meaning its speed and direction remain unchanged. On a position-time graph, this is represented by a straight line with a constant slope. In the given graph, the segment from point 'b' to 'c' shows a straight line with a positive slope, indicating constant and positive velocity.
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Related Practice
Textbook Question

A physics professor leaves her house and walks along the sidewalk toward campus. After 55 min, it starts to rain, and she returns home. Her distance from her house as a function of time is shown in Fig. E2.102.10. At which of the labeled points is her velocity zero?

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Textbook Question

A physics professor leaves her house and walks along the sidewalk toward campus. After 55 min, it starts to rain, and she returns home. Her distance from her house as a function of time is shown in Fig. E2.102.10. At which of the labeled points is her velocity constant and negative?

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Textbook Question

A physics professor leaves her house and walks along the sidewalk toward campus. After 55 min, it starts to rain, and she returns home. Her distance from her house as a function of time is shown in Fig. E2.102.10. At which of the labeled points is her velocity decreasing in magnitude?

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Textbook Question

A car is stopped at a traffic light. It then travels along a straight road such that its distance from the light is given by x(t)=bt2ct3x(t)=bt^2-ct^3, where b=2.40b = 2.40 m/s2 and c=0.120c = 0.120 m/s3. Calculate the instantaneous velocity of the car at t=0t = 0, t=5.0t = 5.0 s, and t=10.0t = 10.0 s.

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Textbook Question

A car is stopped at a traffic light. It then travels along a straight road such that its distance from the light is given by x(t)=bt2ct3x(t)=bt^2-ct^3, where b=2.40b = 2.40 m/s2 and c=0.120c = 0.120 m/s3. Calculate the average velocity of the car for the time interval t=0t = 0 to t=10.0t = 10.0 s.

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Textbook Question

A turtle crawls along a straight line, which we will call the xx-axis with the positive direction to the right. The equation for the turtle's position as a function of time is x(t)=50.0x(t) = 50.0 cm + (2.002.00 cm/s)tt − (0.06250.0625 cm/s2)t2t^2. Find the turtle's initial velocity, initial position, and initial acceleration.

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