question_answer 8)

On a two-lane road, car A is travelling with a speed of . Two cars B and C approach car A in opposite directions with a speed of  each. At a certain instant, when the distance AB is equal to AC, both being 1 km, B decides to overtake A before C does. What minimum acceleration of car B is required to avoid an accident?  

Answer:

At the instant when B decides to overtake A, the speeds of three cars are     Relative velocity of C w.r.t. A,    Time that C requires to just cross A   Fig. 3.85   In order to avoid the accident, B must overtake A in a time less than 40 s. So, for car B we have Relative velocity of car B w.r.t. A,               As                           or            or              Thus  is the minimum acceleration that car B requires to avoid an accident.