Question

Q. 5. A driver of a car travelling at 52 kmh-l applies the brakes and accelerates uniformly in the opposite direction. The car stops in 5 s. Another driver going at 3 kmh 1 in another car applies his brakes slowly and stops in 10 s. On the same graph paper, plot the speed versus time graph for two cars. Which of the two cars travelled further after the brakes were applied​

Answer 1

Answer:

First Car  A:  

Initial Velocity= u= 52 km/hr=52x5/18=14.4 m/s

Final velocity= V= 0m/s

time =t=5sec

Refer attachment for Graph :

Distance travelled : Area of traingle AOB =1/2 OB x AO

=(1/2)x 14.4 x 5=72/2=36m

Second Car  B:

Initial Velocity= u= 3 km/hr=3x5/18=0.83m/s

Final velocity= V= 0m/s

time =t=10sec

Refer attachment for Graph :

Distance travelled : Area of traingle COD =1/2 OD x CO=(1/2)x 0.83 x 10=4.1m

So, after applying of brakes , Car A has travelled a distance of 3m and car B has travelled a distance of 4.1m.

∴ Car B has travelled farther than Car A after the brakes are applied.