In Exercise 17, cars A and B travel the same road. A\'s speed is rkm/h, and B\'s
ID: 3093544 • Letter: I
Question
In Exercise 17, cars A and B travel the same road. A's speed is rkm/h, and B's speed is s km/h (r < s). When will B overtake A ineach situation? Let t = A's time.17) A and B start at the same time, but A starts p km in frontof B.
Thank you.
17) A and B start at the same time, but A starts p km in frontof B.
Thank you.
Explanation / Answer
Since s>r, we can say that B is faster than A. Hence, B canpossibly overtake A. We need a little understanding of constant velocity motions toanswer this. We must note that when there is a constant velocity, D= vt where D is the distance/displacement travelled and v is therate, and of course t is the time. When B overtakes A, it means that they have travelled the samedistance. Hence, D is equal. We can set up two equations: for car A rt+p = D (because A is ahead by p) for car B st = D Hence st = rt + p We are required to solve for the time so we solve for t. Hence t = p/(s-r)