a car A travelling along a straight level road with a uniform speed of 60 km/hr. it is followed by another car B which is travelling uniformly at 70 km/hr. when the distance between them is 2.5km, the car b decelerates at 20 km/hr sq. where will B catch up with A?
Asked by shreeyarokade
1st April 2018,
12:40 PM
Answered by Expert
Answer:
car-A travels at a speed of 60 km/hr. car-B travels at a speed of 70 km/hr. Let us consider car-B travelling ahead and the distance between car-A and car-B is 2.5 km when car-B started decelerating at 20 km/(hr)2. Let, after travelling X km in t hours, car-B catches up car-A. We can write the equation of motion as follows.
for car-A : X = 70×t - (1/2)×20×t2 ...............(1)
for car-B : 60×t = x+2.5 ......................(2)
by eliminating X in (1) and (2), we get 60×t-2.5 = 70×t-(1/2)×20×t2 ...............(3)
Solving for t in (3) we get t = (1+√2)/2 = 1.207 hr and X = 69.92 km
Answered by Expert
1st April 2018,
2:24 PM
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