Concept explainers
Knowing that the coordinates of the utility pole are
(a)
Time elapsed from first collision to the stop at
Answer to Problem 14.20P
The time elapsed from first collision to stop at pole is
Explanation of Solution
Given:
Speed of car B is
Speed of car C is
Weight if car A is
Weight of car B is
Weight of car C is
Coordinates of utility pole are
Concept used:
Draw the diagram for the system mentioned as shown below:
Assume origin as point O where, Car A and Car B collides.
Write the expression for the mass center of first collision.
Multiply the whole equation (1) with
Here,
Write the expression for conservation of momentum for the system.
Multiply the equation (3) with
Here,
Write the expression for the position of pole
Here,
Calculation:
Substitute
Equate
Equate
Substitute
Substitute
Substitute
Equate
Rearrange the above expression for
The time elapsed from first collision to stop at pole is
Conclusion:
Thus, the time elapsed from first collision to stop at pole is
(b)
Speed of car A.
Answer to Problem 14.20P
The velocity of car A is
Explanation of Solution
Calculation:
Substitute
Substitute
Equate the
Substitute
Simplify above expression for
The velocity of car A is
Conclusion:
Thus, the velocity of car A is
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Chapter 14 Solutions
Vector Mechanics for Engineers: Dynamics
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