Question

A car travelling at a speed of 30 km/h is brought to a halt in
4 m by applying brakes. If the same car is travelling at 60 km/h,
it can be brought to halt with the same braking power in
(a) 8 m (b) 16 m
(c) 24 m (d) 32 m

Answer 1

Answer:

Explanation:

Well the question is very simple

Convert all the measurements in S.I units first...

30 km/hr = 30 X 5/18 = 150/18 m/s

60 km/hr = 60 X 5/18= 300/18 m/s

Now this goes with direct proportion

if Speed is 150/18 m/s -------> Distance required to stop = 4 m

if Speed is 300/18 m/s -------> Distance required to stop = x m

therefore by cross multiplication

150/18  X  x  =  300/18 X 4

x= 300/18 X 4

       150/18

x= 300 X 4

      150

therefore x = 2 X4 = 8 m

therefore the car will take a distance of 8 m to stop completely if it is moving with speed of 60 km/hr..

well you could do this question without converting units of speed to S.I units as it is direct proportion !

Hope this helps You !!!!!