what is terminal velocity?
what is terminal velocity?
When a solid sphere falls through a highly viscous liquid, it experiences three forces.
One is the gravitational force (i.e. weight of the body) which acts downwards, W = mg = Vσg
Where, V is volume of the object, and σ is the density of material of the object.
Another is buoyant force , which always act in upward direction, and equal to the weight of the volume displaced by the object.
Thus, FB = VÏg, where, Ï is the density of the liquid.
It also suffers an upward drag force due to viscosity of the liquid which increases while going down which is given by,
F = 6πηrv, where, η is coefficient of viscosity, r radius of sphere, and v velocity at a given instant.
As it depends on the value of v, it increases as the sphere falls down. For a certain value of v the sum of drag force and buoyant force becomes equal to the weight. This is the case of equilibrium.
Vσg = VÏg + 6πηrvt
or 6πηrvt = Vg (σ - Ï)
This velocity vt is called terminal velocity.
When a solid sphere falls through a highly viscous liquid, it experiences three forces.
One is the gravitational force (i.e. weight of the body) which acts downwards, W = mg = Vσg
Where, V is volume of the object, and σ is the density of material of the object.
Another is buoyant force , which always act in upward direction, and equal to the weight of the volume displaced by the object.
Thus, FB = VÏg, where, Ï is the density of the liquid.
It also suffers an upward drag force due to viscosity of the liquid which increases while going down which is given by,
F = 6πηrv, where, η is coefficient of viscosity, r radius of sphere, and v velocity at a given instant.
As it depends on the value of v, it increases as the sphere falls down. For a certain value of v the sum of drag force and buoyant force becomes equal to the weight. This is the case of equilibrium.
Vσg = VÏg + 6πηrvt
or 6πηrvt = Vg (σ - Ï)
This velocity vt is called terminal velocity.
