Question

the time at 0 degree longitude is 9 am,what shall be the at 15 degrees east longitude at that moment​

Answer 1

Solution:

Step 1. The earth takes 4 min to rotate through 1 degree of longitude.

Hence, the earth will take 240 minutes to rotate through 60 degrees of longitude ( 60×4)

Or the earth will take 4 hours to rotate through 60 degrees of longitude. ( 240/60)(since 1 hour=60 minutes).

Thus, we can say that the difference in time between the places lying on 60 degree east longitude and prime meridian(0 degree) is 4 hours.

Step 2: as the prime meridian lies towards the west of 60 degree east longitude, so the GMT will be 4 hours behind to the local time at 60 degree east longitude i.e. 8A.M in the morning.( 12P.M _ 4 hours)

Step3: now we need to find the difference in time between the places lying on 30 degree west longitude and prime meridian i.e.( 30×4=120 minutes or 2 hours( 120/60).

Hence, the time difference between places lying on prime meridian( 0 degree longitude) and places lying on 30 degree west longitude is 2 hours.

As the places lying on 30 degree west longitude lie towards the west of prime meridian, so the local time at 30 degree west longitude will be 2 hours behind the time at prime meridian.

Thus, the local time at 30 degree west longitude will be 6A.M in the morning ( 8A.M _ 2 hours).