Forces and Motion

Force

• A push or pull that causes an object to change its motion
• Measured in Newtons (N)
• Can be contact force (e.g., friction, normal force) or non-contact force (e.g., gravity, magnetism)

Acceleration

• Rate of change of velocity
• Measured in meters per second squared (m/s²)
• Describes how quickly an object's velocity changes
• Produced by a net force acting on an object

Mass

• Measure of an object's resistance to changes in its motion (inertia)
• Measured in kilograms (kg)
• Does not change, regardless of location or velocity

Inertia

• Tendency of an object to resist changes in its motion
• Objects at rest stay at rest, and objects in motion stay in motion, unless acted upon by an external force
• Directly proportional to an object's mass

Friction

• Contact force that opposes motion between two surfaces
• Types:
  • Static friction: prevents an object from moving
  • Kinetic friction: opposes an object's motion
  • Rolling friction: opposes an object's rolling motion
• Depends on:
  • Normal force between surfaces
  • Surface roughness
  • Velocity of the object

Newton's Second Law of Motion

• F = ma
• Force (F) is equal to the mass (m) of an object multiplied by its acceleration (a)
• Describes the relationship between force, mass, and acceleration