JEE PYQ: Waves And Sound Question 46
Question 46 - 2019 (12 Jan Shift 2)
A passenger train of length 60 m travels at a speed of 80 km/hr. Another freight train of length 120 m travels at a speed of 30 km/h. The ratio of times taken by the passenger train to completely cross the freight train when: (i) they are moving in same direction, and (ii) in the opposite directions is:
(1) $\frac{11}{5}$
(2) $\frac{5}{2}$
(3) $\frac{3}{2}$
(4) $\frac{25}{11}$
Show Answer
Answer: (1)
Solution
Total distance to cross $= 60 + 120 = 180$ m.
Same direction: relative speed $= 80 - 30 = 50$ km/h. Time $= \frac{180}{50} \times \frac{1}{1000/3600}$
Opposite direction: relative speed $= 80 + 30 = 110$ km/h.
Ratio $= \frac{110}{50} = \frac{11}{5}$
BETA
