Layering.
Hope this helps (:
-Payshence xoxo
Answer:
The two factors are:
• The kind/type of surface involved.
• The force that the surface are being pushed together.
Explanation:
Friction can be said to be the general term used to describe the force that one surface exert on another when they rub against each other.
When the surface is partially not smooth or totally rough, a greater force is been needed to move one surface past the other.
The weight of the can also significantly be a key factor. This is where the need to friction reduction come to play a role; and need for friction reducers like lubricant, rollers etc helps.
Macrophages
Using the receptors on their surface and through the facilitation by immunoglobulins that attach to the foreign matter, macrophages 'hold' the foreign bodies in the body and 'ingest' them through phagocytosis. Lysozymes in the cells then in 'digest' the foreign matter.
