This is a mind map about Chapter 7 of Physics, summarizing the definitions,
nature,
Three elements, gravity,
Elasticity,
Elasticity and plasticity, etc.
As long as an object changes its state of motion or shape, it must be acted upon by a force.
If an object is acted upon by a force, the object will either change shape, change state of motion, or both.
Change the motion state of an object
Speed size
direction of movement
Change the shape of an object
nature
The effects of forces between objects are mutual
For a force to occur, there must be two or more objects
The effects of forces between objects occur and disappear at the same time, with no order of precedence.
Objects that are not in direct contact with each other can also exert forces.
Three elements
size
direction
point of action
The effect of influence
elasticity and plasticity
deformation
Any object can deform, some deformations are more obvious, and some deformations are extremely small.
Change of shape: A change in the appearance of an object under force
Change in volume: Change in the volume of an object under force
Elasticity: The characteristic of an object deforming under force and returning to its original shape when no force is applied is called elasticity
Plasticity: The object cannot automatically recover after deformation. The characteristic of the original shape is called plasticity.
Elastic limit: When the deformation of an elastic object reaches a certain value, the object cannot return to its original shape even if the external force is removed.
Elasticity
The effect of an object on an object causes the object under force to elastically deform. The force generated by the object under force returning to its original shape is called elastic force.
Generate conditions
Two objects are in contact with each other
elastic deformation occurs
elements
Size: Within the elastic limit, the greater the elastic deformation, the greater the elastic force. When the elastic deformation disappears, the elastic force also disappears.
Direction: Opposite to the deformation direction of the object
gravity
definition
The force produced by the earth's attraction to objects
Three elements
size
The greater the mass of an object, the greater the gravity it experiences. The gravity experienced by an object is proportional to its mass.
G=mg
direction
The direction of gravity is always vertical downwards
point of action
center of gravity
The height of the center of gravity affects the stability of the object. The higher the center of gravity, the lower the stability of the object.
An object with uniform mass distribution and regular shape
geometric center
Thin plate objects with uneven mass distribution and irregular shapes