Measurement of mass

Physics presentation

Measuring Mass• Mass is the amount of matter in an object

• Matter is some thing that has mass and takes up space

• Measurement of mass one of the mist frequently carried out operation

• Accurate mass measurement required for such purpose as

- Obtain a known quantity of Sample for analysis

- Preparation of analytical reagents

- Preparation of calibration standards

Units for measuring mass

• In the international system (SI) of measurement unit base unit of mass is the kilogram (Kg)

• Kilogram is one of the seven base measurement units

• In routine analytical work, it is more convenient to work in terms of grams (g) where 1000 g = 1 Kg or 1 g = 10-3 Kg

MASS MEASUREMENT

• Other sub-division and multiples of the gram are

Unit Symbol Relationship to the gram

Fematogram fg 1fg = 10-15 g

Picogram pg 1pg = 10-12 g

Nanogram ng 1ng = 10-9 g

Microgram Mg 1Mg = 10-6 g

Milligram mg 1mg = 10-3 g

Gram g 1g = 1 g

Kilogram kg 1Kg = 103 g

(metric) tonne t 1t = 106 g

Tools for measuring Mass

• The triple beam balance

How to use a triple beam balance

• 1) Make sure that the balance scale is at zero.

• 2) Place object on balance scale the larges and move the largest rider one notch at a time until the beam drops. Move the rider back one notch (make sure it lock in place)

• 3) Move the next largest rider until the beam drops. Back it up one notch.

• 4) Move the smallest rider until the beam swings equally above and below the zero mark.

• 5) Add up all the numbers to find the mass!

Beam balance

Mass Vs Weight

Mass does not depend on gravity

The mass of an object always remains the same

Weight depends on gravity

Weight equals Mass X gravity

The weight of an object changes if the pull of gravity changes

Answer the following

• _________does not depend on gravity.

• ______________of an object changes if the pull of gravity changes.

• Name any 2 tools used to measure mass.

General questions…

• What is gravitational pull? In what way weight has a relation with the gravitational pull?

• What is weight?

• What is matter?

Complete the table

Unit

Fematogram

Picogram

Nanogram

Microgram

Symbol

Done by, Akhil and group