In mechanics, a force is that which causes a change in velocity or, if you prefer, that which causes an acceleration. When more than one force acts on an object it is the net force that is important. Since force is a vector quantity, use geometry instead of arithmetic when combining forces.
Quick Answer. A crawling sensation felt on the skin may be caused by a condition called morgellons, according to WebMD. Common symptoms of morgellons include feeling like bugs are crawling on the skin, burning, itching and stinging sensations. In some cases skin sores may appear as well.
Paresthesia is an abnormal sensation such as tingling, tickling, pricking, numbness or burning of a person's skin with no apparent physical cause. The manifestation of a paresthesia may be transient or chronic. The most familiar kind of paresthesia is the sensation known as pins and needles or of a limb falling asleep. A less well-known and uncommon but important paresthesia is formication, the sensation of bugs crawling underneath the skin. This term was created by Joseph Blakeley.