Question

a train starting from a a station acquires a speed of 90 km/h in 25 minutes it contineus to move with uniform speed for 2 hourse the brakes are applies and it comes to rest in 25 minutes find the total distance covered

Answer 1

Explanation:

firstly distance covered in first 25 min.=25×90/60

=35.5km

distance covered in 2hrs=90×2

=180km

distance covered in last 25 min.=25×90/60

=35.5

total distance covered=35.5+180+35.5=221km

Answer 2

The total distance covered by the tarin is 236.2 km.

Explanation:

The distance travelled by the tarin in 25 min is,

$d=vt=(90\times10^3m/3600s)\times25\times60s$

d = 37.5ckm.

Now train moves further with uniform speed for 2 h, so distance covered is

$d_1=(90\times10^3m/3600s)\times2\times60\times60s$

d_1 = 180 km.

And finally comes to rest in 25 min, so use equation of motion as

v = u + a t

here u is initial velocity,  u  = 90 km/h = 25 m/s and v = 0 because train comes to rest.

Therefore,

0 = 25 m/s + a x (25 x 60 s)

a = - 0.0167 m/s^2.

distance traveled in this peroid,

$v^2=u^2+2as$

$0=(25m/s)^2-2\times0.0167m/s^2 s$

$s=\frac{25\times25}{2\times0.0167}$

s = 18.7 km.

Hence, total distance = d + d_1 + s

=37.5 km + 180 km + 18.7 km

= 236.2 km.

Thus, the total distance covered by the tarin is 236.2 km.

#Learn More: speed, distance and time.

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