Two trains $100 \; m$ and $120 \; m$ long are running in the same direction with speeds of $72 \; km/h$ and $54 \; km/h$. In how much time will the faster train cross the second (in $; s$)?

$A$ train $240 \; m$ long passed a pole in $24 \; s$. How long (in $s$) will it take to pass a platform $650 \; m$ long?

How long (in $seconds$) does a train $110 \; m$ long running at a speed of $72 \; km/hr$ take to cross a bridge $132 \; m$ in length?

In what time (in $sec$) will a train $100 \; m$ long cross an electric pole,if its speed is $144 \; km/hr$?

Two stations $P$ and $Q$ are $110 \; km$ apart on a straight line. One train starts from $P$ at $7 \; am$ and travels towards $Q$ at $20 \; km/h$ speed. Another train starts from $Q$ at $8 \; am$ and travels towards $P$ at a speed of $25 \; km/h$. At what time will they meet?

$A$ train $75 \; m$ long overtook a person who was walking at the rate of $6 \; km/h$ and passed him in $7 \frac{1}{2}$ seconds. Subsequently,it overtook a second person,and passed him in $6 \frac{3}{4}$ seconds. At what rate (in $km/h$) was the second person travelling?