Math and Geography
in Action
1 revolution of Earth = 365.25 days
6 hours x 4 years = Leap year
& we catch up
1 rotation of Earth = 24 hours
Circle = 360°
North
Pole
360° /24 = 15° = 1 hour
Earth rotates 15° each hour
At the equator Earth ≈ 24,900 miles
= 1037.5 miles in an hour
15°
SUBTRACT an hour
for each time zone
as you move WEST
-
ADD and hour
for each time zone
as you move EAST
0
+
Your place
of origin
The deviation of time
keeping from the
standard time zone in
which a place is
geographically
located.
The usual deviation
occurs in quarter hour
increments, i.e. 15
minutes, 30 minutes,
or 45 minutes.

Areas of the world on
non-standard time
◦
◦
◦
◦
◦
◦
◦
◦
◦
2 South Pacific islands
India
Afghanistan
Nepal
Iran
Sri Lanka
Newfoundland
Central Australia
Myanmar (Burma)
USING WHAT YOU HAVE LEARNED
True or False:
If EVERY part of the statement is TRUE, write T.
If ANY part of the statement is FALSE, write F.
1. The earth makes one complete rotation every 24 hours.
2. For every 15° of longitude, there is a difference of one hour in time.
3. Time zones always have straight boundaries.
4. It is 12 noon everywhere on the earth at the same time.
5. The letters a.m. stand for the 12 hours before 12 noon.
6. Post meridiem means the 12 hours after 12 noon.
7. The line of longitude at 180° is called the Prime Meridian.
8. When you travel across the International Date Line you stay in the
same day.
9. When you cross the Prime Meridian, you stay in the same day.
10. It takes one hour for the earth to rotate 15°.
1.
2.
3.
4.
5.
6.
7.
8.
9.
In what areas of the world do you find non-standard time?
You are in New York and you want to call someone in Rome, Italy, at noon
Rome time. When would you call?
Assume that flying from New York to London requires 6 hours. When
would a flight leaving New York on a Wednesday at 6:00 p.m. arrive in
London?
You are flying from Los Angeles to Moscow. You leave Los Angeles at
10:00 a.m. on Saturday and you arrive in Moscow on Sunday at 9:00 a.m.
How many hours did you actually spend flying?
You are planning a flight from Bombay, India, to Washington, D.C., that
must connect through several cities. You will leave Bombay on August 2,
at 8:00 A.M., and will continue directly through Beijing and Los Angeles to
Washington, D.C. What time is it in Washington, D.C., when you begin your
trip? What will be the date when you arrive in Washington, D.C.?
If it is 3:00 p.m. in Greenwich, what time is it in Moscow?
If it is 9:00 A.M. in Cape Town, what time is it in Washington, D.C.?
If it is Tuesday, 4:30 p.m. in Japan, what day and time is it in Honolulu?
If it is Friday, 8:15 A.M. in Rio de Janeiro what day and time is it in Beijing?