GATE2016 EC-3: GA-5

Question

It takes $10$ s and $15$ s, respectively, for two trains travelling at different constant speeds to completely pass a telegraph post. The length of the first train is $120$ m and that of the second train is $150$ m. The magnitude of the difference in the speeds of the two trains (in $m/s$) is ____________.

• A. $2.0$
• B. $10.0$
• C. $12.0$ 
• D. $22.0$

Answer 1

Let $x$ and $y$ be the speeds of the two trains.

• $x = \frac{120}{10}=12\;m/s$
• $y = \frac{150}{15}=10\;m/s$

So, magnitude of their difference in speeds $ = \mid12-10\mid = 2 \;m/s$

Correct Option: A.

Answer 2

It takes 10 s and 15 s, respectively, for two trains travelling at different constant speeds to completely pass a telegraph post. The length of the first train is 120 m and that of the second train is 150 m. The magnitude of the difference in the speeds of the two trains (in m/sm/s) is ____2 m/s________.

speed=150/15 - 120/10 =|10 -12|=2 m/s