Class 9th Physics Chapter 6
Mechanical Properties of Matter
In the pervious class we study about the matter and every thing is
surrounding our us is made of matter. Here we can study about the matter
exert the force, pressure and density.
Deformation of Solids
Deformation of solid is change the shape, size or volume when the external
force act on it
Types of Deformation
• Elastic Deformation
• Plastic Deformation
Example
A rubber band is applying force it changes size and volume.
Hooke’s Law
It is stated that the force is applied to stretch and compress x has been
found is applied is directly proportional to the applied force with in the
elastic limit.
The SI unit of Hooke’s Law is Nm-1.
Derivation
Force is applied to a body and spring
extension is exceeding x
According to Hooke’s Law
𝐹 ∝x
Remove the promotion sign
, 𝐹 = 𝑘x
Therefore,
𝐹
𝑘=
x
Application of Hooke’s Law
• Spring Scale
• Balance of Mechanical Clock
• Galvanometer
Density
Density is defined as the mass per
volume.
𝑲𝒈
The SI unit of the density is .
𝒎𝟑
𝑚
𝜌=
𝑉
Density Measurement
Density of substance can be determined by the mass and volume.
Find the volume
𝑉 = 𝑙x𝑤xℎ
Pressure
Pressure is defined as the force exerted normally on unit area of an object.
The SI unit of pressure is Pascal (Pa).
1 Pa = 1 Nm-1
𝐹
𝑃=
𝐴
Mechanical Properties of Matter
In the pervious class we study about the matter and every thing is
surrounding our us is made of matter. Here we can study about the matter
exert the force, pressure and density.
Deformation of Solids
Deformation of solid is change the shape, size or volume when the external
force act on it
Types of Deformation
• Elastic Deformation
• Plastic Deformation
Example
A rubber band is applying force it changes size and volume.
Hooke’s Law
It is stated that the force is applied to stretch and compress x has been
found is applied is directly proportional to the applied force with in the
elastic limit.
The SI unit of Hooke’s Law is Nm-1.
Derivation
Force is applied to a body and spring
extension is exceeding x
According to Hooke’s Law
𝐹 ∝x
Remove the promotion sign
, 𝐹 = 𝑘x
Therefore,
𝐹
𝑘=
x
Application of Hooke’s Law
• Spring Scale
• Balance of Mechanical Clock
• Galvanometer
Density
Density is defined as the mass per
volume.
𝑲𝒈
The SI unit of the density is .
𝒎𝟑
𝑚
𝜌=
𝑉
Density Measurement
Density of substance can be determined by the mass and volume.
Find the volume
𝑉 = 𝑙x𝑤xℎ
Pressure
Pressure is defined as the force exerted normally on unit area of an object.
The SI unit of pressure is Pascal (Pa).
1 Pa = 1 Nm-1
𝐹
𝑃=
𝐴
