Question

a car travelling at a speed of 30 km/hr is brought to halt in 8 m by applying brakes if the same car is travelling at 60km/hr it can be brought to halt with the same breaking power in how much distance?

Answer 1

Hello! So, in this question, two cases are given.In the first case, speed and stopping distance is given. So, we find out the retardation/maximum braking force.Stopping distance(s)=-(u^2)/2aBut, the speed is in kmph and has to converted into m/s We get 30 kmph=8.3 m/s Substituing in stopping distance formula we get 8(distance given)=-(8.3)^2/2aSolving for a, we get a=-4.3 m/s^2Now, in the second case, we have the maximum braking force and the speed and we have to find stopping distance.Convert the speed to m/s which gives 60 kmph = 16.6 m/s.Substitute in stopping distance formula, we get-(16.6)^2/-4.3=s After solving, we get s=32 m So answer is 32m.Hope this helped.