beam balance

Mass is the quantity of matter in a substance. Matter is anything that occupies space.

The mass of an object depends on it’s size and the number of particles it contains.

The SI unit of mass is the Kilogram (Kg).

A kilogram is the mass of a piece of platinum-iridium metal kept at Sevres, near Paris,France at the International Office of Weights and measurements. That piece of metal kept in France is the standard with which all masses of the world are measured with the kilogram unit.

though kilogram is the SI unit, the most common unit of measuring mass is the gram.

The following table shows sub-units of gram and kilogram

Prefix	number of grams (g)
Kilogram (Kg)	1000 g
Hectogram (Hg)	100 g
Decagram (Dg)	10 g
decigram (dg)	(1/10) g
centigram (cg)	(1/100) g
milligram (mg)	(1/1000) g
microgram (µg)	(1/1000,000) g
nanogram (ng)	(1/100,000,000) g
picogram (pg)	(1/1000,000,000,000) g

tables of conversion of grams

1 kg = 1000 tonnes

other units used to measure mass includes:

1 pound (lb) = 0.4536 kg)
1 ounce(oz) = 0.02835kg

Though different weights are experienced depending on gravitational pull of a place, the mass of an object remains constant beacuse number of particles in an object will not change with change of location.

Instruments used to measure mass

Platform balance

Electronic balance

The object whose mass is to be measured is placed on the pan and its weight causes electronic circuit to develop current to display the mass on the digital display. It is a very accurate instrument and is useful in laboratories especially small masses.

works by the principles of moments.

The object whose mass is to be measured is balanced against a known standard mass on as equal arm lever. The beam balances when the mass of the object is equal to the standard mass.

Table balance

works under principles of moments

Spring balances

uses laws of gravitational pull

postal balance

Roman Steelyard Balance

Exercise

convert the following as instructed

1500 tonnes to kg
200000000000 mg into Kg.
256 g into tonnes
0.000000000000000000 567 tonne into pg
12.43 g into mg

Problems involving mass

Sheila went to the grocery store and bought a 3 watermelons that weighed 4.4 kilograms and a bunch of bananas that weighed 750 grams. She also bought a bottle of juice that contained 1.2 liters.

a) Convert the weight of the watermelon from kilograms to grams.

b) If Sarah bought 3 bottles of juice, how many grams of juice did she buy in total if density of juice is 1.25gcm^-3?

c) If each banana weighs 125 grams, how many bananas did Sarah buy?

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MASS