a trian covers a distance of 90km/90min find the time taken by the trian to cross an electric pole if the length of the trian is 300m
Answers
A 180 meter long train at the speed of 90km/h will cross a 320 meter platform in how long?
The problem will be solved using the following formula -
Length of the Train + Length of the Platform (m) = Speed of the Train (m/s) * Time taken to cross the platform (s)
Here,
Length of Train = 180 m
Length of Platform = 320 m
Speed of Train = 90 km/h -> m/s = 90 * 5/18 = 25 m/s (To convert km/h to m/s, we multiply the value by 5/18)
Let the time time taken be train be x.
Using the formula stated above, we get -
180 + 320 = 25 * x
500 = 25 * x
x = 500/25 = 20
Hence, the time taken by the train is 20 seconds.
Answer:
Let original speed =xkm/hr
⇒ Time taken to travel =
x
90
hr
⇒ New speed =(x+15)km/hr
⇒ Time taken to travel =
x+15
90
hr
∴
x
90
=
x+15
90
+
2
1
⇒
x
90
−
x+15
90
=
2
1
⇒ 90(
x
1
−
x+15
1
)=
2
1
⇒
x(x+15)
x+15−x
=
180
1
⇒ 15×180=x(x+15)
⇒ 2700=x
2
+15x
⇒ x
2
+15x−2700=0
⇒ x
2
+60x−45x−2700=0
⇒ x(x+60)−45(x+60)=0
⇒ (x+60)(x−45)=0
Speed can not be negative.
∴ The original speed of the train is 45km/hr