Physics Chapter 3 - Force and Pressure

Contact forces

Two objects physically touch each other. E.g Friction, air resistance, normal force, tension

Non-contact forces

No physical contact. E.g gravitational, electrostatic, magnetic forces

Friction and resistive forces

Oppose motion; slow down moving objects

Mass (Kg)

Amount of matter in the body; always constant

Weight (N)

Gravitational force acting on a mass; changes based on gravitational field strength

Density (kg/m³)

Mass per unit volume

Pressure (Pa)

Force acting per unit area; Higher pressure = higher force (same contact area); Smaller contact area = higher pressure (same force)

Density Formula

density = mass ÷ volume

Pressure Formula

pressure = force ÷ area

Weight Formula

weight = mass × gravitational field strength