Question

a train is traveling at a speed of 90km/h-¹, brakes are applied to produce a uniform acceleration of-0.5m/s-², find how far the train will go before it is brought to rest​

Answer 1

initial velocity (u)=90 km/hr

convert into metre per second =90×1000/3600=25m/s

now, if brakes are applied then train comes to rest

then final velocity(v)=0 m/s.

acceleration (a)=-0.5 m/s

since acceleration is negative so it is called retardation.

now , by third equation of motion, we have

$2as = {v}^{2} - {u}^{2}$

$2 \times - 0.5 \times s =0 - 625$

$- 1 \times s = - 625$

$s = \frac{ - 625}{ - 1}$

$s = 625$

Therefore,the distance is 625 metre.