Question

a train is moving with a velocity of 120 km h -1 .Brakes are applied on the train and its velocity become 70 kilometre h -1 after travelling 100km h-1. How much further will it go before coming to rest?​

Answer 1

Explanation:

$\huge\underline\mathfrak{Answer}$

GIVEN

• Initial velocity,u = 120 km/h
• final velocity,v = 70 kmph
• distance ,s= 100 km

TO FIND

• Distance the train covers before coming to rest

Before finding the distance it covers before it comes to rest,we should calculate the acceleration of the body

Using the third equation of motion,

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

Substituting the values,

${70}^{2} - {120}^{2} = 2a(100)$

$- 9500 = 200a$

$a = - 47.5 {ms}^{ - 2}$

Now ,

u = 70 kmph

s=s

v = 0

a = -47.5 m/s^2

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

${0}^{2} - {70}^{2} = 2( - 47.5)(s)$

$- 4900 = - 95s$

$s = \frac{ - 4900}{ - 95}$

$s = 51.5m$

HOPE IT HELPS YOU...