Question

A train is travelling at a speed of 90km/hr.Brakes are applied so as to produce a uniform acceleration of 2m/sec square .Find how far the train will go before coming to rest
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Answer 1

Given that,

Acceleration a=−0.5m/s2

Speed v=90km/h=25m/s

Using equation of motion,

v=u+at

Where,

v = final velocity

u = initial velocity

a = acceleration

t = time

Put the value into the equation

Finally train will be rest so, final velocity,v=0

0=25−0.5t

25=0.5t

t=0.525​

t=50 sec

Again, using equation of motion,

S=ut+21​at2

Where, s = distance

v = final velocity

u = initial velocity

a = acceleration

t = time

Put the value into the equation

Where S is distance travelled before stop

s=25×50−21​×0.5×(50)2

s=625 m

So, the train will go before it is brought to rest is 625 m.