Vehicles

Vehicles are non-living means of moving. They are most repeatedly man-made (e.g. bicycles, cars, motorcycles, trains, ships, and aircraft), although some other means of transportation which are not made by man can also be called vehicles; examples include icebergs and balanced tree trunks. Vehicles may be propelled by animals, e.g. a chariot or an ox-cart. However, animals on their own, though used as a earnings of transportation, are not called vehicles. This includes humans transport another human, for example a child or a disabled person.

Vehicles that do not pass through on land are often called crafts, such as watercraft, sail craft, aircraft, hovercraft and spacecraft. Movement lacking the help of a vehicle or an animal is called locomotion. The word vehicle itself comes from the Latin vehicular.

Voltage

Voltage is the difference of electrical potential between two points of an electrical or electronic circuit, uttered in volts. It measures the potential energy of an electric field to source an electric current in an electrical conductor. Depending on the difference of electrical potential it is called extra low voltage, low voltage, high voltage or extra high voltage.

Between two points in an electric field, such as exists in an electrical circuit, the distinction in their electrical potentials is known as the electrical potential difference. This difference is proportional to the electrostatic force that tends to drive electrons or other charge-carriers from one point to the other. Potential difference, electrical potential, and electromotive force are measured in volts, leading to the commonly used term voltage. Voltage is usually represented in equations by the symbols V, U, or E.

Electrical potential difference can be thought of as the capacity to move electrical charge through a resistance. At a time in physics when the word force was used loosely, the potential difference was named the electromotive force or EMF—a term which is still used in confident contexts.

Anatomical basics of the human lip

One differentiates between the Upper and lower lip. The lower lip is usually somewhat larger. The border between the lips and the surrounding skin is referred to as the vermilion border, or simply the vermilion. The vertical groove on the upper lip is known as the philtrum.

The skin of the lip, with three to five cellular layers, is very thin compared to typical face skin, having up to 16 layers. With light skin color, the lip skin contains no melanocyte. Because of this, the blood vessels appear through the skin of the lips, which leads to their notable red coloring. With darker skin color this effect is less prominent, as in this case the skin of the lips contains more melanin and thus is visually thicker.

The lip skin is not hairy and does not have sweat glands or sebaceous glands. Therefore, it does not have the usual protection layer of sweat and body oils which keep the skin smooth, kill pathogens, and regulate warmth. For these reasons, the lips dry out faster and become chapped more easily.