Question

A train passes 210 m long bridge in 21 s and a signal in 20 s.
Find the speed of the train in km/h. please help me.​

Answer 1

Answer:

Answer is 58.33 km/hr

Total Distance of the bridge = 210 + x

length of signal = x

so ,

length of train = 210 + ×/21 = ×/20 (cross multiply)

= × = 4200

now , to find speed

(4200 + 210) - 4200

4410 - 4200

210/1s

210 in km/hr

210×18/5

58.33

Answer 2

Answer:

756 km/h

Step-by-step explanation:

Let length of train be x

Since, Speed =Distance/Time

and speed is assumed equal

210+x/21 = x/20

21 × x = 20(210 + x) (cross multiplied)

21x = 4200 + 20x (shift 20x to the RHS)

21x - 20x = 4200

x = 4200

therfore, length of train = 4200 m

Speed of train = 210 + 4200/21

= 210 m/s

To convert m/s into km/h

= 210 × 18/5

= 756 km/h