Solution:

We know that the Earth revolves about its axis once every 24 hours. In other words, the Sun completes its apparent revolution of 360o in 24 hours. This means that the Sun crosses each of the 360 meridians of longitude once every 24 hours.

So, in 1 hour, the Sun appears to move 15o,

in 4 minutes, it appears to move 1o,

in 1 minute it appears to move 15′,

in 4 seconds it appears to move 1′.

From this, it becomes obvious that there is a direct relationship between arc and time such that 1 minute of time equals 15 minutes of arc