A thermometer is an instrument used to measure temperature. The equal divisions on the thermometer are known as degrees. Temperature is usually measured in degree Celsius. The temperature of two common substances ice and boiling water is at 0 degree Celsius and 100 degree Celsius respectively.

Types of thermometers:

• Clinical thermometers
• constant volume gas thermometer
• thermocouple thermometer
• Platinum resistance thermometer

At first it was agreed that all organisms should be classified into two kingdoms, the plant and animal kingdom. But until recently it was discovered that all organisms fall into two natural groups known as prokaryotes and eukaryotes. These two terms refer to differences in the location of DNA.

Prokaryotes:- In these organisms cells lack true nuclei because the DNA is not enclosed by a nuclear membrane and just lies freely in the cell membrane.

Eukaryotes:- The cells of these organisms are formed from prokaryotes but they do have a true nuclei.

The Table below shows the differences between prokaryote and eukaryote.

When two waves interact to produce a weaker wave or a stronger wave Interference is said to have occured.
There are two things that must take place for interference to occur: 

1. The sources of these waves must have a constant phase difference and the same frequency. This is called Coherent.
2. Also these waves must have the same amplitude.

Advantages of Mammals storing Lipids rather than Carbohydrates

• Lipids produce more metabolic water when burned compared to carbohydrates.
• More energy is produced from lipids when they are metabolically broken down.
• Lipids are insoluble but carbohydrates are water-soluble. This is why lipids are not easily dissolved out of the cell unlike carbohydrates. This contributes to the phospholipid bi layer in cell membrane.
•  Lipids are more useful where insulation is required because it retains more heat.
• Lipids also protect delicate organs because they can be used as packing material around organs.

The phospholipid bi layer is a  molecule consisting of  a fatty acid chain at one end of the molecule and a glycerol-phosphate-nitrogen group at the other end. It is found in the cell membrane and has polar (water loving) and non-polar (water hating) characteristics.

Here is an example on how to solve a vector question:


Example #1:

A force of 3N acts at an angle of 90 degrees to a force of 4N. Find the magnitude and direction of there resultant R.

( Note: a line similar to the 3N was drawn on right to make the vector tail to head. The resultant line R was then drawn from the tail of 4N line to Head of 3N line on right. Also note that direction in this case is the unknown angle. )


Answer


Using Pythaoras' theorem to find magnitude.

A Vector can be defined by capital letters at both ends or by one lower case letter.

The sum of two or more vectors is called a resultant.

• When vectors are in the same directions we add.

Example #1.

• When vectors are in opposed directions we minus.

Example #2

Difference Between Scalar and Vector

Scalars have magnitude only but Vectors have both magnitude and direction.

The table below displays some of the most popular scalar and vector quanities.

S.I Units

Mass --> Grams (g), or Kilograms(Kg)

Length --> Meter(m)

Time --> Seconds(s)