How to do this?

Question

Using the longitude of Kuala Lumpur which is 101 E, calculate the local time when the local solar time is 12:00. Please explain the reason.

Answer 1

This may be the way to go: local solar time of 12:00 is when the sun is overhead at Kuala Lumpur. The "local time" is probably the standard time for the time zone. Time zones are centered every 15 degrees from Greenwich, so the appropriate time zone would be centered at longitude 105 E degrees. With one revolution of 360 degrees in 24 hours, the difference from standard longitude of 4 degrees is 4/360 = 0.0111 * 24 hour * 60 min/hour = 16 minutes.

Because 101 E is less far east from England than 105 E, the sun rises 16 minutes later than at the center of the time zone. Thus the standard time must be 11:44, when the sun was overhead at 105 E longitude. It takes 16 more minutes until it is overhead at 101 E.