A car leaves regularly from point A for point B every 10 min. The distance between A and B is 60 km. The car travel at a speed for 60 km/h. Find the number of cars that a man driving from B to A will meet enroute if he starts from B simultaneously with one of the cars leaving A. The car from B travels at a speed of 60 km/h.
Time taken for car to travel from B to A is:
T=sv=6060=1 hr=60 min
Distance between any two consecutive cars leaving from A is constant and is given by:
s=10/60×60=10 km
Relative speed between any car leaving from A and car leaving from B is vr=60−(−60)=120 km/hr
Hence, on crossing one car, next car is met in time,
t=sv=10120 hr=5 min
Hence, total number of cars met are:
n=Tt=12
This excludes the first car met at B. Hence, car starting from B meets a total of 13 cars.