MindMap Gallery Functional principles and conservation laws of particle groups
This is a mind map about the functional principles and conservation laws of particle groups. The main contents include the kinetic energy theorem of particle systems, functional principles and conservation laws, summary of this chapter, collisions, and spatial accumulation laws of research forces.
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This is a mind map about bacteria, and its main contents include: overview, morphology, types, structure, reproduction, distribution, application, and expansion. The summary is comprehensive and meticulous, suitable as review materials.
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.
This is a mind map about the reproductive development of animals, and its main contents include: insects, frogs, birds, sexual reproduction, and asexual reproduction. The summary is comprehensive and meticulous, suitable as review materials.
Functional principles and conservation laws of particle groups
The kinetic energy theorem of a system of particles
particle kinetic energy theorem
work of force, power
achievement
Constant force work
The power of changing force
power
Instantaneous power
average power
The kinetic energy theorem of a system of particles
Note here that when solving the problem of the momentum theorem before, we integrated over time. The internal forces were vector summed and then integrated. The total effect was zero.
The sum of the work of forces and the sum of the work of forces are not the same thing
Internal force analysis
Characteristics of a pair of internal strength skills
The sum of the work of a pair of internal forces has nothing to do with the selection of the reference system
Select the most convenient reference frame to calculate the work done by a pair of internal forces
The most convenient calculation method is given here: select one of the objects as the reference frame (the reference frame has nothing to do with inertia or non-inertia)
Conservative and non-conservative forces
conservative internal force
non-conservative internal force
Object system potential energy
Introducing the potential energy function
Inverse problem: Determine the corresponding conservative force from the potential energy function
Determine system stability based on potential energy function
Conservative force work = potential energy function increment negative value
Selection of potential energy origin
potential energy curve
Functional principles and conservation laws
Functional Principle of Matter System
Derivation
Comparison of kinetic energy theorem and functional principle of particle system
Conservation of mechanical energy in point systems
Both situations satisfy the conditions
Kinetic energy relationship of particle system under static system and center of mass system
Fireworks and firecrackers were tied up and exploded in the air.
Review: We discussed momentum before. The momentum in the center of mass system is zero.
Now: Discuss kinetic energy. There is kinetic energy in the center of mass system and there is also kinetic energy in the static system.
Koenig's theorem
Functional principle of particle system under center of mass system
Important examples
principle of conservation of energy
Closed system: You can always choose a system so that the system is not affected by external forces
under closed system
The work done by the external force is zero
The meaning of the principle of conservation of energy:
Communicated between mechanics and other disciplines
Energy rich
chapter summary
collision
Characteristics of collision
Short time, small displacement, ignore position changes
During the period, the interaction force is a variable force, and the average force is often used to find the force.
Momentum conserved during collision
One-dimensional collision process and classification
perfectly elastic collision
imperfectly elastic collision
perfectly inelastic collision
law of collision
Derivation
Corresponding to three collision situations
Advice on solving completely elastic collision problems
Previous: Solving for post-collision velocity, simultaneous conservation of momentum and conservation of mechanical energy (with squares, tedious calculations)
Now: simultaneous conservation of momentum and collision law (restitution coefficient equals 1)
Some explanations on the law of collision
The recovery coefficient e is only related to the material
The law of collision can be extended to oblique collision, and it holds true for any normal direction of the point of action of two objects.
Each velocity in the collision law is expressed by coordinates perpendicular to the surface direction, that is, the velocity of each point has positive and negative
2D collision
The spatial accumulation law of research power
One question and three solutions (familiar with the application of kinetic energy theorem and functional principles)
particle kinetic energy theorem
The kinetic energy theorem of a system of particles
Functional Principle of Matter System