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.
Force is a quantitative description of an interaction that causes a change in an object's motion. An object may speed up, slow down, or change direction in response to a force. Objects are pushed or pulled by forces acting on them. Contact force is defined as the force exerted when two physical objects come in direct contact with each other. Other forces, such as gravitation and electromagnetic forces, can exert themselves even across the empty vacuum of space.