Terminal speed

Definition

Terminal speed is the constant speed that a freely falling object eventually reaches when the resistance of the medium prevents further acceleration. It occurs when the force of gravity is balanced by the drag force in a viscous fluid.

5 Must Know Facts For Your Next Test

1. Terminal speed is achieved when gravitational force equals the drag force acting on an object.
2. It depends on factors such as object's mass, shape, and the viscosity of the fluid.
3. The drag force can be described by Stokes' law for small spherical objects moving at low velocities.
4. Terminal speed increases with an increase in object's mass and decreases with an increase in fluid's viscosity.
5. In biological contexts, terminal speed affects how organisms like microorganisms move through different fluids.

Review Questions

• What forces are balanced when an object reaches terminal speed?
• How does increasing the viscosity of a fluid affect an object's terminal speed?
• Explain how Stokes' law relates to terminal speed for small spherical objects.

Related terms

Drag Force: The opposing force exerted by a fluid on an object moving through it, proportional to velocity at higher speeds.

Stokes' Law: $$F_d = 6\pi \eta r v$$, describing the drag force experienced by small spherical objects moving slowly in a viscous fluid.

Viscosity: A measure of a fluid's resistance to flow or deformation, affecting how objects move through it.