$A$ train $300 \ m$ long is running with a speed of $54 \ km/h$. In what time will it cross a telephone pole? (in $seconds$)

Walking $\frac{6}{7}$ of his usual speed, a man is $12 \, \text{minutes}$ late. The usual time taken by him to cover that distance is

$A$ person travelled a certain distance by train at a speed of $25\, km/h$ and walked back at a speed of $4\, km/h$. The whole journey took $5\, hours\, 48\, minutes$. What distance did he travel? (in $km$)

$A$ man leaves a point $P$ and reaches the point $Q$ in $4 \, hours$. Another man leaves the point $Q$,$2 \, hours$ earlier and reaches the point $P$ in $4 \, hours$. Find the time in which the first man meets the second man (in $hours$).

$A$ train $180 \, m$ long is running at a speed of $90 \, km/h$. How long will it take to pass a post? (in $sec$)

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 $km/h$):