## Thursday, August 20, 2009

The fasting month of Ramadhan is fast approaching. It was confirmed today that the fasting month will start this Saturday. I love the month of Ramadhan. Everything seems so relaxed and peaceful during this month. I don't have to rush like the regular days. I don't have to think about what to eat for breakfast and lunch. I also seem to eat less in this month and thus feel much healthier. Fasting is good for our health. We are able to enjoy the food we have coz we were deprived of it for the whole day. We humans like to take things for granted. We never appreciate the things that we have. Everyone will also make a point to make it home on time to break fast together. Thus the fasting month is also good in strengthening the family ties.

Tomorrow is also the last day of school before the school holidays. The school will be closed for holiday for 1 week from 22 - 31 August. The form 4 classes just finished the August test on Tuesday, so I gave them a day off from lessons on Wednesday. I had to carry on with my lessons with my 5SA class coz the trial exam will start on the 4th of August and I still have a few topics on Earth As A Sphere to cover.

So on Monday, I taught the girls how to find the distance between 2 point on the meridian. These are the steps:

1. Find the difference in angle between the two points.
2. Use the formula Distance = difference in angle x 60 to obtain the distance.

The unit for distance on the sphere is nautical miles (nm). The same steps can be used if you want to find the distance between two points on the equator.

Problem 1 : Find the distance between the following points :

A (85°N , 105°E) and B (27°N, 105°E)

Solution :

Note that points A and B are on the same longitude or the same meridian.

Step 1 : Find the difference in angle between the 2 points. Since the 2 points are in the same hemisphere, substract the latitude of both points to obtain the difference in angle between 2 latitudes.

Difference in angle is (85 - 27) = 58°.

Step 2 : Use the formula Distance = 58 x 60 = 3360 nm.

Problem 2 : Find the distance between the following points

A (30°S , 50°W) and B (15°N , 50°W)

Step 1 : Find the difference in angle. Since the 2 points are in a different hemisphere, we have to add the angles of the two latitudes to obtain the difference between the 2 points.

Thus the difference in angle is (30° + 15°) = 45°

Step 2 : Distance = 45 x 60 = 2700 nm.

The same steps can be use to find the distance between 2 points on the equator.

Example : Find the distance between A (0° , 14°E) and B (0° , 15°W)

1. Difference in angle (14 + 15) = 29 - Different side of the meridian
2. Distance = 29 x 60 = 1740 nm