Question

12. Brakes are applied to a train travelling at 72 km/h. After passing over 200 m, its velocity reduces to 36 km/h.
At the same rate of retardation, how much further will it go before it is brought to rest ?​

Answer 1

Answer:

66.6666667m

Explanation:

Initial speed:- 72000m/3600s=20m/s

Final Speed:-36000m/3600s=10m/s

Distance travelled:- 200m

Let retardation=r

therefore, 100=400-400r(v^2=u^2+2as)

300=400r

r=3/4 m/s^2

Final speed =0

Initial speed= 10m/s

r=3/4m/s^2

therefore, using v^2=u^2+2as

0=100-3/2s

3/2s=100

s=100*2/3

s=66.6666667m