This is a conceptual question involving Fluid Mechanics and Buoyancy . 1. Let\'s
ID: 1415153 • Letter: T
Question
This is a conceptual question involving Fluid Mechanics and Buoyancy.
1. Let's say you have a motionless block on a flat surface. The summation of forces in the y-direction is the following:
FN - FG = ma --> FN = FG
When learning Newtonian Mechanics, the summation above is correct. However, why is buoyant force EXCLUDED from the summation of forces? Isn't the Air exerting a buoyant force onto the block, upwards? If so, why is buoyant force not included in the summation? Alot of Physics books also exclude it, so there must be a reason. Is Newtonian Mechanics, practiced, in a vacuum? Such that the block is not surrounded by any type of fluid?
How about the classical problem of a block sliding down an inclined plane? Isnt Air exerting a buoyant force onto the block as it slides down?
Explanation / Answer
It is generally not used because in these cases, Buoyant force << other classical forces, it is not taken into consideration. But when air drag force is considerable, then we take into account of this force.