In 1884 the Greenwich Meridian (0° Longitude) was internationally fixed and all other lines of longitude were defined from this line.

As the earth has to rotate through 360° in 24 hours, it means that each
 corresponds to a one hour time difference.

In practice, as on Sheet 3a, the time zones are modified to suit borderlines and groups of countries. For example, China lies between 75°E and 135°E, but the whole country uses Standard Beijing Time, which is Greenwich Time +8 hours.

Problem 1  How many 1 hour time zones should China lie in?

Problem 2  It takes a British Airways plane 9½ hours to fly from London Heathrow to Beijing. If the plane leaves Heathrow at 14.00, at what time will it arrive at Beijing? After a 3 hours stop at Beijing, it returns to Heathrow, again taking 9½ hours. At what time will it land back at Heathrow?

Table 1 below gives the current total flying times between London Heathrow and various international locations.

Problem 3        Use the Time Zone Map (Sheet 3a) to find the arrival time (in local time) at each destination for a 10.00 departure time from London.

Problem 4        If a plane leaves Brisbane at 10.00 on a Monday and flies directly eastwards to San Francisco, with a total journey time of 18 hours, when will it arrive (local time)?
 Flying Time Brisbane London London Heathrow San Francisco Table 1 Table 2 to (hours) 08.00 00.00 16.00* Brisbane 28 12.00 04.00 20.00* Delhi 9 .... 08.00 .... Moscow 3 .... 12.00 Tokyo 12 .... 16.00 San Francisco 11 .... 20.00 .... Johannesburg 11½ .... .... .... * Previous day

Problem 5       Table 2 above starts to summarise the time differences throughout the day between three locations. Copy and complete the table.

Problem 6        A company has branches in Brisbane, London and San Francisco. Suggest a suitable time for a telephone conference between the branch managers?

EXTENSION  On a world map which shows the major countries, draw one hour time zones. Table the time differences for major countries and then compare your answers with the actual values given on Sheet 3a.