Two cars starf simultaneously from the same place and in same direction . The first car moves with a uniform speed of 10 km/h . The second car moves at a speed of 8km/hr in the first hour and then increases its speed by 0.5 km/hr in each succeeding hour . If both the cars move non stop , then how long will it take for the second car to overtake?
Member since Apr 11 2014
Consider the second car overtake the first car by t hours.
∴ Distance covered by first car = distance covered by second car.
10t = 8 + ( 8 + 1/2 ) + ( 8 + 2/2) + ( 8 + 3/ 2) + --------------------+ ( 8 + (t - 1) / 2)
10t = 8t + (1/2) [ 1 + 2 + 3 + ................+ ( t - 1)]
2t = (1/2)[ t (t -1) / 2]
8t = [ t2 - t ]
t2 = 9t
∴ t = 9 as t ≠ 0
∴ the second car overtake the first car by 9 hours.