Concept explainers
A student drives a moped along a straight road as described by the velocity-versus-time graph in Figure P2.12. Sketch this graph in the middle of a sheet of graph paper. (a) Directly above your graph, sketch a graph of the position versus time, aligning the time coordinates of the two graphs. (b) Sketch a graph of the acceleration versus time directly below the velocity-versus-time graph, again aligning the time coordinates. On each graph, show the numerical values of x and ax for all points of inflection. (c) What is the acceleration at t = 6.00 s? (d) Find the position (relative to the starting point) at t = 6.00 s. (e) What is the moped’s final position at t = 9.00 s?
Figure P2.12
(a)
The graph of the position versus time, aligning the time coordinates with the given velocity versus time graph.
Answer to Problem 12P
The graph of the position versus time, aligning the time coordinates with the given velocity versus time graph is
Explanation of Solution
Assume that
From the velocity versus time graph in Figure P2.12, the inflection points are
Write the equation for the final position of a particle moving in one dimension under constant acceleration.
Here,
From the velocity versus time graph, the velocity of the particle at
Substitute
From
Write the equation for the final position of a particle moving with constant velocity in one dimension.
Here,
From the velocity versus time graph, the constant velocity at
Substitute
From
From the velocity versus time graph, the velocity of the particle at
Substitute
From figure P2.12, after
The graph of the position versus time, aligning the time coordinates with the given velocity versus time graph is shown in figure 1.
Conclusion:
Thus, the graph of the position versus time, aligning the time coordinates with the given velocity versus time graph is shown in figure 1.
(b)
The graph of the acceleration versus time, aligning the time coordinates with the given velocity versus time graph and to show the numerical values of
Answer to Problem 12P
The graph of the acceleration versus time, aligning the time coordinates with the given velocity versus time graph is
Explanation of Solution
Write the equation for the acceleration.
Here,
Substitute
In the interval
The slope of the velocity versus time curve changes abruptly at the points of inflection
Substitute
The graph of the acceleration versus time, aligning the time coordinates with the given velocity versus time graph is shown in figure 2.
Conclusion:
Thus, the graph of the acceleration versus time, aligning the time coordinates with the given velocity versus time graph is shown in figure 2.
(c)
The acceleration at
Answer to Problem 12P
The acceleration at
Explanation of Solution
The acceleration is given by equation (III). The particle is under constant acceleration during
Conclusion:
Substitute
Therefore, the acceleration at
(d)
The position of the moped at
Answer to Problem 12P
The position of the moped at
Explanation of Solution
The particle is under constant acceleration during
Conclusion:
From the position versus time graph, the position of the particle at
Substitute
Therefore, the position of the moped at
(e)
The position of the moped at
Answer to Problem 12P
The position of the moped at
Explanation of Solution
The particle is under constant acceleration during
Conclusion:
From the position versus time graph, the position of the particle at
Substitute
Therefore, the position of the moped at
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Chapter 2 Solutions
Principles of Physics
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- Principles of Physics: A Calculus-Based TextPhysicsISBN:9781133104261Author:Raymond A. Serway, John W. JewettPublisher:Cengage Learning