🌈 Essential physics class 7 icse Physical quantities and measurement

Density

Introduction-

 Which one is more heavy? 1 kg of cotton or 1 kg of iron.Answer is both equal. Next which is more dense 1kg of cotton or 1 kg of iron? Now answer is Iron. To understand this let's learn a term Density .  Density is the measure of how much matter is in a given amount of space.

🌈  Mindmap Density 

● Definition - Mass per unit volume.

● Formula- Density = Mass÷ Volume

● Factors- 1. directly proportional to Mass

                 2. Inversely proportional to volume

●Units- S.I - kg/ m³

            C.G.S- g/cm³

●  1 g/ cm³ = 1000 kg/ m³

● Regular bodies - mass is found out using balance and volume by using formula

● Irregular bodies- mass is found out using balance and volume by water displacement method 

🌈 Rainbow mindmap Relative density 

● Definition- Relative density of a substance is the ratio of density of a substance to the density of water

● Relative Density of a substance = Density of a substance ÷ Density of  water

● Relative density of a substance = Mass of a substance of certain volume ÷ Mass of same volume of water..

● R.D has no unit.

● Density = R.D g/cm³ 

                 = R.D'x1000 kg / m³

●  Relative density of water is 1 .

●     If  R.D of a body is more   than  1, it will sink in water.

        If R.D of a body  is less than 1 , it will float in water. 

Activities 

Activity 1

To find Area of a irregular surface by using graph paper

Activity 2

To find volume of irregular body by water displacement method. 

Activity 3

To find volume of cube.

Activity 4

To grind volume of cylinder 

Activity 5- 

To find  volume of a cubiod.

Activity 6

To study Hydrometer

Solution- Essential Physics ICSE class 7 ch - Physical Quantities and measurements 

To know more about Density

To know  mass of a body

To know  weight of a body

Check your knowledge 

Google forms

What is Relative density of water?

Relative density of water is 1

What is the density of water at 4 degree centigrade?

The density of water at 4 degree centigrade is 1000 kg per meter cube.

Body will float or sink if density of body is equal to density of water?

Body will float just below the surface of water.

What is the S.I. unit of weight of the body?

newton

What is the weight of the body at the center of the earth

Weight of the body at the center of the earth is zero.