MindMap Gallery law of conservation of momentum
The law of conservation of moment of momentum, also known as the law of conservation of angular momentum. It refers to the inference based on the Moment of Moment Theorem that when the total external moment is 0, its momentum moment remains unchanged.
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This is a mind map about plant asexual reproduction, and its main contents include: concept, spore reproduction, vegetative reproduction, tissue culture, and buds. The summary is comprehensive and meticulous, suitable as review materials.
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law of conservation of momentum
momentum
Invariants in collisions
One-dimensional collision
The product of mass and velocity remains unchanged
momentum
p=mv
Momentum change amount (final amount-initial amount)
Momentum and kinetic energy
Definition
p=mv E=1/2mv²
Targetedness
vector scalar
Conversion relationship
p=√2ME E=½MV²
Momentum and speed
When V changes, ΔP will definitely change
momentum theorem
momentum theorem
Impulse
I=Ft
N·S
Vector
The direction of the force is constant
The I direction is the same as the force direction
change in direction of force
The direction of I is the same as the change direction of the object's momentum at the corresponding time.
Impulse and work
In a certain process, the impulse of a variable force is zero, and the work is not necessarily zero.
In a certain process, the impulses of the action force and reaction force are equal, and the total work is not necessarily zero.
momentum theorem
FΔT=MΔV
application
Momentum changes by a certain amount
The shorter the action time, the greater the force
step
Clarify the research object
Force analysis
To find the resultant impulse
Find the initial and final states
column momentum theorem equation
The principle of selection of kinetic energy theorem and Newton's second law
The sum of external forces is constant force
Priority kinetic energy theorem
multi-process problem
The kinetic energy theorem can solve the whole process
Niu Erdecomposable Process
fluid problems
ΔM=ΡSΔL=ΡSVΔt
The law of conservation of momentum stipulates the positive direction
System, internal force, external force
System: a whole composed of two (or more) interacting objects
Internal force: the force between objects in the system
External force: the force exerted by objects outside the system on objects within the system
law of conservation of momentum
condition
Not subject to external force
The net external force is zero
Internal force is much greater than external force
established in a certain direction
expression
ΔP=0
Universality
vectoriality
application
m₁v₁ m₂v₂=m₁v₁′ m₂v₂′
step
Clarify system components
Force analysis
Specify the positive direction and determine whether it is conserved
Specify the positive direction and determine the initial and final momentum.
Plug in the data and get the result
critical case
spring
closest to each other
equal speed
Elastic potential energy is maximum
The largest loss of kinetic energy
Slider-cart
equal speed
Maximum relative displacement
Generates maximum heat energy
The largest loss of kinetic energy
Slider-Bevel
The slider has the smallest speed in the vertical direction
equal speed
Maximum gravitational potential energy
The largest loss of kinetic energy
Three basic viewpoints and five rules for solving mechanical problems
dynamic perspective
Kinesiology
v=v₁ at
x=v₁ ½at²
Niu Er
F=ma
energy perspective
Kinetic energy theorem
law of conservation of mechanical energy
momentum view
momentum theorem
law of conservation of momentum
Selection principles
subject to constant force
dynamic perspective
Movement changes due to sustained force
Momentum Theorem (Time)
Kinetic Energy Theorem (Displacement)
system
conservation of mechanical energy
Conservation of momentum
recoil phenomenon rocket
Features
Movement in the opposite direction under the action of internal force
The system is not subject to external forces or the internal forces are much greater than the external forces
Kinetic energy increases
Follow the law of conservation of momentum
man ship model
Conservation of momentum
People walk and the boat goes, people stop and the boat stops, people go fast and the boat goes fast, people go left and the boat goes right
mx₁-Mx₂=0
x₁ x₂=L
Solve the problem together
bullet hits wood block
bullet lodged in block of wood
Conservation of momentum
Mechanical energy loss (friction heat generation)
Fd=½mv₁²-½ (m M)v₂² d is the depth of the bullet injected into the wood block
The bullet penetrated the block of wood
Conservation of momentum
Mechanical energy loss (friction heat generation)
FL=½mv₁²-½ (m M)v₂² L is the length of the wood block
When two objects have the same velocity, it is a completely inelastic collision.
Elastic and inelastic collisions
elastic collision
Conservation of momentum
Conservation of kinetic energy
m₁v₁=m₁v₁′ m₂v₂′
½m₁v₁²=½m₁v₁′² ½m₂v₂²
From the above, we can get: v₁′=(m₁-m₂)÷(m₁ m₂)v₁ v₂′=2m₁÷(m₁ m₂)v₁
inelastic collision
Conservation of momentum
Kinetic energy is not conserved
perfectly inelastic collision
Conservation of momentum
Kinetic energy is not conserved
in conclusion
Small hit, big hit, bounced back
The big one hits the small one and runs towards
Equal masses, elastic collision, v exchange
possibility judgment
step
Conservation of momentum
Does kinetic energy increase?
Realistic
Movement in the same direction before collision v after v > v before
Reciprocal motion before collision v front′ ≥ v back′
Spring-ball model
Spring shortest/longest: similar to perfectly elastic collision
Spring returns to original length: similar to elastic collision
Small ball-slope model
Highest point: Similar to perfectly inelastic collision
Separation: Similar to elastic collision
Experiment: Verify the law of conservation of momentum
Study the conservation of momentum when the slider on the air cushion guide rail collides
Study the momentum of the ball at the end of the chute when it collides