Two cars A and B start together in the same direction from the same place . The first goes with uniform speed of 40km/hr . The second goes at a speed of 36km/hr in the first hour and increases the speed by 1km/hr each succeeding hour . After how many hours will the second car overtake the first car if both car go non-stop ?

Guest Jul 8, 2020

#1**+1 **

Let's look at the *differences* in speed each hour.....

hour

1 2 3 4 5 6 7 8 9 10

diff

-4 -3 -2 -1 0 1 2 3 4 5

so at hour 5 they are the same speed....then the originally slower train starts gaining so that at hour 9 it has made up the miles it lost in the first 4 hours of going slower

at hour 9 they should be at the same point

check: 9 hr (40 km/hr) = 360 km

other train 36 + 37 +38 +39 +40 +41 +42 + 43 + 44 = 360 km

ElectricPavlov Jul 8, 2020