http://www.yourdiscovery.com/video/mythbusters-top-10-is-yawning-contagious/
A video on yawning
http://www.howstuffworks.com/question572.htm
A article explaining about yawning
Tuesday, March 30, 2010
Physics lesson 2.3 (measuring volume)
To measure the volume of the liquids we can use the measuring cylinder ,burette or the pipette.
Meniscus
In narrow glass cylinders, the liquid is curved into a shape called a meniscus.
Meniscus can be either a concave or a convex.A concave meniscus occurs when the molecules of the liquid is attracted to the container more than to each other.(e.g.water)Conversely,A convex meniscus occurs when the liquid molecules have stronger attraction yo each other than to the container.(e.g.mercury)
Surface tension
This is caused by cohesion(the attraction of molecules to other molecules)
To read the accurate volume, ensure that your eye level is the same as the bottom of the meniscus curve.
Meniscus
In narrow glass cylinders, the liquid is curved into a shape called a meniscus.
Meniscus can be either a concave or a convex.A concave meniscus occurs when the molecules of the liquid is attracted to the container more than to each other.(e.g.water)Conversely,A convex meniscus occurs when the liquid molecules have stronger attraction yo each other than to the container.(e.g.mercury)
Surface tension
This is caused by cohesion(the attraction of molecules to other molecules)
To read the accurate volume, ensure that your eye level is the same as the bottom of the meniscus curve.
Physics lesson 2.3 (Measurement of Area& Volume)
Area
Only tick a box if more than half of it is shaded
Volume
LIQUIDS:Using the measuring cylider ,burette and pipette ,we can measure the volume of the liquids
Physics lesson 2.2 [Vernier Calipers (Zero Error)]
Zero error is when the jaws of the vernier calipers are fully closed ,and the zero marking on the vernier scale does not coincide with the zero marking on the main scale .
When the zero marking on the vernier scale is on the right of the main scale, it is called a positive zero error.To calculate the accurate measurement, subtract the zero error from the original reading.
When the zero marking on the vernier scale is on the left of the main scale ,it is called a negative zero error .To calculate the accurate measurement, add the zero error from the original reading.
When the zero marking on the vernier scale is on the right of the main scale, it is called a positive zero error.To calculate the accurate measurement, subtract the zero error from the original reading.
When the zero marking on the vernier scale is on the left of the main scale ,it is called a negative zero error .To calculate the accurate measurement, add the zero error from the original reading.
Physics lesson 2.1 (Vernier Calipers)
Vernier Calipers are used to measure short lenghts and diameters of objects of up to 10 cm.
They consist of the outside jaws ,inside jaws ,main scale reading ,vernier scale reading and the taill.
Using the vernier calipers :
1. Close the jaws of the vernier calipers . Ensure that the zero marking on the vernier scale is in line with the zero marking on the main scale.
2.Place the object within the jaws of the vernier calipers and clamp it firmly in place.
3.Read the length
They consist of the outside jaws ,inside jaws ,main scale reading ,vernier scale reading and the taill.
Using the vernier calipers :
1. Close the jaws of the vernier calipers . Ensure that the zero marking on the vernier scale is in line with the zero marking on the main scale.
2.Place the object within the jaws of the vernier calipers and clamp it firmly in place.
3.Read the length
Monday, March 29, 2010
Physics lesson 1(Measurement of units)
Q: Why does metres have to be metres and not any other unit?
A:Metres is used as it is internationally recogninsed thus it would avoid confusion.
Elaboration:Metre is the SI base unit of distance .Originally,the meter was designed to be one-tenth of a quadrant the distance between the equator and the north pole . For a long time ,the metre was precisely defined as the length of an actual object, a bar kept at the International Bureau of Weights and Measurements in Paris.In recent years,however,the SI base units (with one exception) have been redefined in abstract terms so they can be reproduced to any desired level of accuracy in a well equipped laboratory.
A:Metres is used as it is internationally recogninsed thus it would avoid confusion.
Elaboration:Metre is the SI base unit of distance .Originally,the meter was designed to be one-tenth of a quadrant the distance between the equator and the north pole . For a long time ,the metre was precisely defined as the length of an actual object, a bar kept at the International Bureau of Weights and Measurements in Paris.In recent years,however,the SI base units (with one exception) have been redefined in abstract terms so they can be reproduced to any desired level of accuracy in a well equipped laboratory.
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