Concept explainers
Car A is traveling at 40 mi/h when it enters a 30 mi/h speed zone. The driver of car A decelerates at a rate of 16 ft/s2 until reaching a speed of 30 mi/h, which she then maintains. When car B, which was initially 60 ft behind car A and traveling at a constant speed of 45 mi/h, enters the speed zone, its driver decelerates at a rate of 20 ft/s2 until reaching a speed of 28 mi/h. Knowing that the driver of car B maintains a speed of 28 mi/h, determine (a) the closest that car B comes to car A, (b) the time at which car A is 70 ft in front of car B.
(a)
The closest that car B comes to car A.
Answer to Problem 11.76P
Explanation of Solution
Given information:
When,
For,
The v-t curve of two cars is as shown:
At,
Acceleration of A,
And,
Again, similarly acceleration of B,
Car B will continue to overtake car A while
For his time interval,
Then at,
Thus,
(b)
The time at which car A is 70 feet in front of car B.
Answer to Problem 11.76P
Explanation of Solution
Given information:
When,
For,
The v-t curve of two cars is as shown:
At,
Acceleration of A,
And,
Again, similarly acceleration of B,
Car B will continue to overtake car A while
For his time interval,
Then at,
Thus,
Since,
Then for,
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Chapter 11 Solutions
Vector Mechanics For Engineers
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