04. Forces

Types of Forces

• Static friction
  • Frictional force between surfaces at rest with respect to each other.
  • It increases with increasing applied force up to a maximum value (which is proportional to normal contact force).
• Kinetic friction
  • Frictional force acting between surfaces in relative motion.
• Viscous forces
  • Resistive force experienced by a solid moving in a fluid.
  • Dependent on speed of object v, e.g. $$F_D\propto v$$ at low speeds and $$F_D\propto v^2$$ at high speeds.