Definition: The effect of one object on another object

Interpretation

The effects of forces between objects are mutual (the object is both a force-exerting object and a force-receiving object)

Deform, change state of motion

Size (represented by the length of the line segment)

Direction (indicated by arrow direction)

Point of action (represented by the starting point of the line segment)

Principle: The elongation of the spring is proportional to the tension

Instructions for use: Return to zero, do not exceed the range, stand vertically upward, line of sight is perpendicular to the scale surface, remain stationary or move evenly when reading.

Definition: The force exerted on an object due to the attraction of the earth is called gravity

Force object: Earth, direction: vertically downward

Center of Gravity: The point where gravity acts on an object

The mass of an object is proportional to gravity

At the same place, the ratio of the object's gravity to its mass is a certain value, usually 9.8N/kg, called g

g increases with latitude and altitude, and g varies from planet to planet.

same direction

opposite direction

Balance: An object is at rest or moving in a straight line at a uniform speed (equilibrium state)

Balance force: The force on an object when it is in equilibrium

Definition: When an object slides relative to the surface of another object, a phenomenon occurs that hinders relative sliding.

Size: equal to the pulling force

Direction: Opposite to the direction of movement

Influencing factors: pressure, roughness, material properties

Increase beneficial friction: increase pressure, increase roughness

Reduce harmful friction: reduce pressure, reduce roughness, change sliding to rolling

Conditions of occurrence: Two objects are in contact with each other and have a tendency of relative motion.

Three elements: point of action, direction, size

Range: 0~f large

The property of an object to maintain uniform linear motion or rest is called inertia

All objects have inertia under any circumstances

The amount of inertia an object has is related to its mass

When the initial velocity of an object is the same, the smaller the resistance it receives, the smaller the distance the object moves, and the slower the velocity changes.

All objects always remain at rest or in a state of uniform linear motion until an external force forces it to change this state (Newton's first law)

The motion of an object does not require force to maintain it. Force is what changes the state of motion of an object.