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.
Since you mention gravity and mass, this normal force must be the reaction to a weight. Well, that normal force is equal (and of opposite direction) to the the weight mg when the surface which the body rests on is a fixed horizontal plane. mass when placed in a gravitational field will experience a force equal to its mass times the magnitude of the field. The direction of the force will be the same as the direction of the gravitational field.