The wheel of an engine is $3 \frac{3}{4}$ metres in circumference and makes $4$ revolutions in $2$ seconds. The speed of the train is (in $km/h$):

$A$ speed of $45\, km/h$ is equivalent to which speed in $m/s$?

$A$ motor car starts with a speed of $70 \, km/hr$ with its speed increasing every $2 \, hours$ by $10 \, km/hr$. In how many hours will it cover $345 \, km$?

Two buses start at the same time from two bus stations and proceed towards each other at the rates of $20 \, km/h$ and $25 \, km/h$ respectively. When they meet,one bus has travelled $80 \, km$ more than the other. Find the distance between the two bus stations (in $km$).

$A$ man travelled a distance of $61 \, km$ in $9 \, h$,partly on foot at the rate of $4 \, km/h$ and partly on bicycle at the rate of $9 \, km/h$. The distance travelled on foot was (in $km$):

Two trains are moving in the same direction at $50 \text{ km/hr}$ and $30 \text{ km/hr}$. The faster train crosses a man sitting in the slower train in $18 \text{ seconds}$. Find the length of the faster train in meters.