A 150m long train is moving with constant velocity of 12.5 m/s. Find

1.	A 150m long train is moving with constant velocity of 12.5 m/s. Find (i) The equation of the motion of the train, (ii) Time taken to cross a pole, (iii) The time taken to cross the bridge of length 850 m is?
Answer» (i) Now m = y/x = 12.5m/second, The equation of the line is y = mx + c … (1) Put c = -150, m = 12.5 m, The equation of motion of the train is y = 12.5x – 150 (ii) To find the time taken to cross a pole we take y = 0 in (1) ⇒ 0 = 12.5x – 150 ⇒ 12.5x = 150 x = 150/12.5 = 12 seconds (iii) When y = 850 in (1) 850 = 12.5 x – 150 ⇒ 12.5x = 850 + 150 = 1000 x = 100/12.5 = 80 seconds

A 150m long train is moving with constant velocity of 12.5 m/s. Find (i) The equation of the motion of the train, (ii) Time taken to cross a pole, (iii) The time taken to cross the bridge of length 850 m is?

Answer»

(i) Now m = y/x = 12.5m/second,

The equation of the line is y = mx + c … (1)

Put c = -150, m = 12.5 m,

The equation of motion of the train is y = 12.5x – 150

(ii) To find the time taken to cross a pole we take y

= 0 in (1)

⇒ 0 = 12.5x – 150 ⇒ 12.5x = 150

x = 150/12.5 = 12 seconds

(iii) When y = 850 in (1)

850 = 12.5 x – 150 ⇒ 12.5x = 850 + 150 = 1000

x = 100/12.5 = 80 seconds