Today we will discuss about measurement of Mass and Weights. These two physical quantities are very important so far measuring other physical quantities are concerned.
MEASUREMENTS OF MASS and WEIGHTS
1. Mass of a body is the quantity of matter contained it.
2. It is a constant quantity and it cannot be zero
3. It is a scalar quantity, which means it has no direction
4. The units of mass
In CGS system: gram
In FPS system: pound
In MKS system: Kg
Multiple and submultiples of Kg
1000 mg = 1g
1000 g = 1Kg
100 Kg = 1 quintal
10 quintal = 1 tonne
Therefore, we can say 1000Kg = 1 tonne
5. Mass is measured in beam balance, physical balance and electronic balance
What is one gram?
Gram: It is the unit of mass in the C.G.S. system. The mass of certain cylindrical piece of platinum-iridium alloy kept in Paris is called a standard kilogram, which is known as the international prototype Kilogram. One thousandth part of Kg. is a gram.
What is one pound?
Pound: It is the standard unit of mass in the F.P.S system. The mass of a certain piece of platinum kept at the standard department of the Board of Trade in England is taken as a pound and is known as the prototype pound.
What is weight?
1. The weight of a body is the force with which the earth attracts the body towards the centre
- It is a variable quantity and it can be zero
- It is a vector quantity, which means it has direction
- The units of weight
In CGS system: dyne
In FPS system: poundal
In MKS system: newton
One kilogram force is the force with which a body of mass 1 kg is attracted towards the centre of Earth
That is Weight of a body of mass 1 kg = 1 kgf = 1 kgxg = 9.8N = 10 N approx.
Weight of a body depends upon gravitational force.
The weight of a body = kgxg (where g = acceleration due to gravity)
Since g is variable so weight is also variable
- Weight is measured by spring balance
How weight changes from place to place
Since the value of g is highest in the poles so the weight is maximum in the poles
Since the value of g is minimal in the equator so the weight is minimum in the equator
Since the value of g decreases as we go higher up in the sky so the weight decreases as we go higher up.
Since the value of g decreases as we go deeper inside the earth’s crust so the weight also decreases as we go deeper inside the earth. Weight of a body is zero at the center of earth.
Since the value of g decreases by 1/6 th in the moon so the weight of a body also decreases by 1/6 th in the moon. Eg if a body on the earth is 24 N then in the moon it will be 4 N
16 drums = 1 ounce (oz)
16 oz = 1 pound (lb)
1 ton = 20 x 4 x 28 = 2240 lb
1 pound = 253.54 gm
1 kg = 2.204 lbs
Differences between Mass and Weight
Point No.1 of mass Point No. 1 of weight
Point No.2 of mass Point No. 2 of weight
Point No.3 of mass Point No. 3 of weight
Point No.4 of mass Point No. 4 of weight
Point No.5 of mass Point No. 5 of weight
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