Class VII : Physics: Physical Quantities and Measurements

Class VII : Physics: Physical Quantities and Measurements

Volume

Definition: The space occupied by an object is called its volume.

Units and their relations :

S.I Unit of Volume: m³

1 m³   =  10⁶ cm³

1 L = 1,000 cm³ = 1,000mL

1mL = 1cm³ = 10^-6 m³

Measurement of Volume of regular objects : Formulae

1. Volume of a cube = (one side) ³
2. Volume of a cuboid = length x breadth x height
3. Volume of a sphere = (4π /3 ) x (radius) ³
4. Volume of  cylinder = π  x  (radius)²  x height
5. Volume of cone = ( π / 3 ) x  (radius)² x height 

Area 

Definition: The surface occupied by an object is called its area. 

Units and their relations :

S. I unit of Area: m²

1 are = 1 square decametre = 10² m²

1 hectare = 10⁴ m²

1 km² = 10⁶ m²

1 cm² = 10^-4 m²

1mm² = 10^-6 m²

Measurement of Area of regular objects: Formulae

1. Area of a squre = (one side) ²
2. Area of a rectangle = length x breadth
3. Area of a circle= π x (radius)² 
4. Surface Area of a cylinder = 2π  x  radius  x length
5. Surface Area of sphere =  4π  x  (radius)²

Density

Definition: The density of a  substance is defined as the mass of a unit volume of that substance.

Density = Mass / Volume

d = M / V

Units and their relations :

S.I Unit of Density = Kg/ m³

C.G.S unit o Density = g/ cm³

1 g/ cm³ = 1000  Kg/ m³

Speed

Definition:  The distance covered by a body in unit time is called the speed of the body.

Speed = Distance traveled / Time taken

Speed (v) = d / t

Units and their relations :

S. I. Unit of time = m/s

1 km/hour = 1/3.6 m/s

3.6 km/h = 1 m/s