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CHAPTER 7: LINEAR MOMENTUM - Coggle Diagram
CHAPTER 7: LINEAR MOMENTUM
Momentum and its relation force
Momentum, p
p=mv (kgm/s)
The rate of change of momentum is equal to the net force
∑F=dp/dt=∆p/∆t
Conservation of Momentum
total before collision =total after collision
m1v1+m2v1=m1v2+m2v2
When external force is zero, total momentum remains constant
Conservation of Energy and Momentum in Collisions
Momentum is conserved in all collisions
Collisions in which kinetic energy is conserved as well are elastic collisions, and those in which it is not are called inelastic
Momentum and kinetic energy is conserved in elastic collisions
Inelastic collisions, momentum is conserved but kinetic energy is not conserved
Collisions and Impulse
During a collision ,objects are deformed due to the large forces involved
Since F=dp/dt , so dp=Fdt
Impulse ,J
When two objects collide,large forces exert on one another for a short period of time.
The impulse is equal to the change in momentum
∆p=pf −pi = ∫Fdt=J
Elastic Collisions in One Dimension
After collision, objects move off with different velocity
Total momentum and kinetic energy is conserved
∑pi=∑pf
∑Ki=∑Kf
For objects with equal mass, the objects exchange velocity after collision
Inelastic Collisions
After collision, the two objects move off together with same velocity
Total momentum is conserved
∑pi =∑pf
m1v1+m2v1=(m1+m2)V
Total Kinetic energy is not conserved
∑Ki≠∑Kf
Some energy is lost and converted to other form of energy
Collisions in Two or Three Dimensions
X-component
Pix=Pfx
Y- component
Piy=Pfy
Problem Solving
Choose coordinate system
Apply momentum conservation
Draw diagram
If collision is elastic, apply conservation of energy
Is there an external force?
Solve
Choose the system
Check units and magnitudes of results
Center of Mass (CM)
The center of gravity is the point at which the gravitational force can be considered to act
Center of Mass and Translational Mass Motion
The total momentum of a system of particle is equal to the product of the total mass and the velocity of the center of mass
MaCM= ∑Fext
System of Variable
