The force on an object due to the attraction of the earth (Gravity is not the universal gravitation force, but a vertical downward component of the universal gravitation force)

G=mg

always straight down

When a deformed object returns to its original shape, it exerts a force on the object in contact with it.

direct contact between objects

Elastic deformation occurs at the contact point

Always opposite to the direction of deformation of the object exerting force

F=kx

definition

Generate conditions

direction

definition

Generate conditions

direction

definition

μ=Ff/FN

determining factors

Always hinders the relative movement trend between objects

definition

relation

parallelogram rule

triangle rule

parallelogram rule

triangle rule

Effect decomposition method

Orthogonal decomposition method

Represents the position change of the particle, which is from the out position to the end position. It is a directed line segment (displacement).

The length of the object’s trajectory (scalar)

Displacement is a vector quantity, and distance is a scalar quantity. Only in one-way linear motion, the magnitude of displacement is equal to the distance.

The ratio of the displacement of an object to the time it takes for this displacement to occur , is a physical quantity that describes how quickly the position of an object changes.

The average velocity direction is the same as the displacement direction, Instantaneous speed direction and direction of object motion

definition

is a scalar

definition

is a vector Same as displacement direction

definition

is a vector Same as the direction of motion of the object, Along the tangential direction of the motion trajectory

The ratio of the change in an object's speed to the time it takes for this change to occur , is a physical quantity that describes how fast an object’s speed changes.

Consistent with the direction of velocity change, The direction of the speed change determines It has nothing to do with the direction of the initial and final velocities.

v=v. at

x=v. t 1/2·at^2

v^2-v. ^2=2ax

The displacement differences within consecutive equal adjacent time intervals T are equal, that is, x2-x1=x3-x2=…=xn-x(n-1)=aT^2

Average speed (time)

Displacement midpoint speed

The ratio of the instantaneous speed at the end of T, the end of 2T, the end of 3T...nT is v1:v2:v3:…:vn=1:2:3:…:n

Within the first T, within the first 2T, within the first 3T,…, the ratio of the displacements within the first nT is x1:x2:x3:…:xn=1^2:2^2:3^2:…:n^2

The ratio of the displacements in the first T, the second T, the third T,...the nth T is x1:x2:x3:...:xn=1:3:5:...:(2n- 1)

The ratio of the time taken to pass through consecutive equal displacements is t1:t2:t3:…:tn=1:root 2-1:root 3-root 2:…:root n-root (n-1)

v=2πr/t

ω=2π/t

(ω^2)r

T=2π/ω

Effect

Fn=m(v^2)/r=mωv=m(ω^2)r=m4(π^2)r/(T^2)=4π^2mf^2r

direction

Kepler's three laws

law of universal gravitation

First cosmic velocity

second cosmic speed

third cosmic speed

GMm/r^2=ma=mv^2/r=mω^2·r=4π^2r/T^2

GM=gR^2

central body mass

central body density

The further away, the slower

double star problem

All objects always maintain uniform linear motion or rest. Unless a force acting on it forces it to change this state

Point out that force is not what maintains motion, It’s the reason that changes the state of motion of an object That is, force is the cause of acceleration

Pointed out that all objects have inertia, Therefore Newton's first law is also called the law of inertia

definition

measure

universality

The acceleration of an object is proportional to the external force it experiences. Inversely proportional to the mass of the object, the direction of acceleration is the same as the direction of the external force

Newton's second law only applies to inertial reference frames, That is, a reference frame that is at rest relative to the ground or moving in a straight line at a uniform speed.

Newton's second law only applies to macroscopic objects and low-speed motion

overweight

weightlessness

Complete weightlessness

content

Features

significance