A train of length 300 m takes 20 s to overtake a cyclist travelling at 18 kmph. Find its speed (in m / s ).

Question

A train of length 300 m takes 20 s to overtake a cyclist travelling at 18 kmph. Find its speed (in m / s ). (A) 20 (B) 25 (C) 15 (D) 12.5

Tardigrade Admin · Accepted Answer

Let its speed be s m / s. A cyclist has negligible length compared to the train. ∴ Time taken by the train to cross the cyclist = Train's length overline text Relative speed ∴ (300/s-(18)((5)18))=20 s-5=15 ⇒ s=20

Q. A train of length $300 m$ takes 20 s to overtake a cyclist travelling at $18 km p h$ . Find its speed (in $m / s$ ).

20

25

15

12.5

Let its speed be $s m / s$ .
A cyclist has negligible length compared to the train.
$∴$ Time taken by the train to cross the cyclist $=$ Train's length
$\overline{Relative speed}$
$∴ \frac{300}{s - ( 18 ) ( \frac{5}{18} )} = 20$
$s - 5 = 15 \Rightarrow s = 20$

Q. A train of length 300m takes 20 s to overtake a cyclist travelling at 18kmph. Find its speed (in m/s ).

20

25

15

12.5

Let its speed be sm/s. A cyclist has negligible length compared to the train. ∴ Time taken by the train to cross the cyclist = Train's length Relative speed ​ ∴s−(18)(185​)300​=20 s−5=15⇒s=20

Q. A train of length $300 m$ takes 20 s to overtake a cyclist travelling at $18 km p h$ . Find its speed (in $m / s$ ).

Let its speed be $s m / s$ .
A cyclist has negligible length compared to the train.
$∴$ Time taken by the train to cross the cyclist $=$ Train's length
$\overline{Relative speed}$
$∴ \frac{300}{s - ( 18 ) ( \frac{5}{18} )} = 20$
$s - 5 = 15 \Rightarrow s = 20$