Green or Dark Yellow Phlegm. A thick and dark yellow phlegm may be a sign of a viral or bacterial infection, sinus infection, or lower respiratory tract infection. Typically, this occurs when the immune system sends white blood cells, known as neutrophils, to the area of infection.ink Phlegm. Pink-colored phlegm is anything but pretty. Coughing up pink phlegm is an indicator of pulmonary edema, also known as fluid in the lungs. It can also be a sign of bleeding when seen in small amounts, which show up as a stain or streak.
The normal force, which is the force that supports the weight of an object on a surface, acts in the opposite direction of gravity. Most often, we see this with objects at rest on a horizontal surface, like a book on a table or someone standing on a floor.
A force in mechanics is a concept that has both a size and a direction. The net force acting on an object is the sum of the forces onto the object, taking into account both their sizes, and their directions. For example, if an object has two forces acting on it, with equal sizes but in opposite directions, then the net force will be zero (technically: a null vector). If instead the forces are of equal size and in the same direction, then the net force is equal to twice either force.