Laws Of Motion , Law of Inertia, Impulse and Impulsive Force
Laws Of Motion
Inertia : It is inherent characteristic due to change its condition of motion.
There are three types of inertia. It is scalar quantity
A: Inertia of rest : The opposition of body due to change its state of rest.
B: Inertia of motion: The opposition of body due to change its state of motion.
C: Inertia of direction: It is inability of a body to change its direction of motion.
Important point -
Mass is the measurement of inertia.
Inertia is depend on mass.
Is push or pull. It changes a condition of motion.
It is a vector quantity.
System of particles:
It is a group of particles having same velocity and fixed distance between them.
It is characteristic of a moving object.
It denoted by P.
It is vector quantity
Si unit of momentum is kgm/sec^2.
Newton’s First Law ( Law of Inertia) :
An object stay at rest or motion continue unless an external force is applied on it.
It defines inertia, force and mechanical equilibrium, Net acceleration of object is zero.
First law gives definition of force.
Newton Second Law:
Rate of change of momentum is directly proportionate to the net external force is applied on object.
Second law gives quantity of force
F∝ mdv/dt. (dv/dt=a)
F∝ ma –eq (i)
F= kma , where k is constant.
If F=1 , m=1 , a=1 then k=1
Putting value of k in equation (i)
Then F= ma.
Si unit of force is
CGS unit = dyne.
One newton =
Force is a vector quantity.
Second Law : Impulse and Impulsive Force
A large number of force can create in very small interval of time.
Impulse = Force × (final time – initial time)
Impulse = Force × Δt
I = F × Δ
Derivation of the Formula
I = refers to the impulse
F = refers to the force of the object
Δt = refers to the change in time
Since the impulse is a measure of how much the momentum changes as a result of a force acting on it for a period of time. Moreover, an alternative formula for impulse is
Impulse = Δp⃗ = p⃗ final – p⃗ initial
Impulse (I) = F x t = m(v-u).
Si unit= Nsec. And kgm/sec.
Dimension = MLT^-1