Force

运动
- 力
  - 杠杆
  - 压强
  - 能量

Scalar标量	Vector矢量/向量
distance距离	displacement位移
speed速率	velocity速度
	acceleration加速度
formular

alt distance-and-velocity alt clicle

Newton's first law:No resultant force, object will remain its state of constant velocity or stationaty.
Newton's second law:
Newton's third law:action and reaction
same magnitude
opposite direction

mass vs height

mass	weight
Scalar	vector
kg	N
constant	change by gravitational field

(field strength)(accelerantion)

friction opposes motion or tendancy of motionAir resistance

Velocity
Area free fall

Moment力矩(旋转)

clockwise(顺)/anti-clockwise(逆) unit:Nm

Principle of moment(POM)

Equilibrium 平衡

Translational 平移=>合力=N
rotational 旋转=>合力矩=0Nm

When a body is in equilibrium,the sum of clockwise moment about any pivot is equal to the sum of anti-clockwise moment about the same pivot.

Centre of Gravity(重心)

suspensin悬挂
- 物体只受拉力和重力
- 平衡=>重心和支点同一线

Stability 稳定性

重心越低越稳
底面积越大越稳

Pressure 压强

固体
液体/气体

压强的应用

hydraulic press 液压机
barometer 大气压
manometer 气压表 Hydraulic press 液压机
- 不可以有气泡/气体，因为气体可压缩compressible
- 液压机使用油，因为油可以润滑减小摩擦,reduce friction Barometer 大气
- ,
- Manometer 气压表