A tightrope walker needs a balance bar to keep balance, which is based on the lever principle. The balance bar in hand is to stabilize the center of gravity of the whole human body, which can be adjusted at any time to ensure that the gravity line of the human body falls on the steel wire.

From the point of view of mechanics, if any object wants to keep balance, its gravity action line (vertical line through the center of gravity) must pass through the supporting surface (the contact surface between the object and the object supporting it). If the line of gravity does not pass through the bearing surface, the object will fall. The condition for a person to stand on the flat ground and not fall (that is, to maintain a stable balance) is that the line of gravity acting through the center of gravity of a person should be in the supporting surface formed by the outer edges of his feet.

Walking is unstable and balanced. When walking, one foot strides forward and the body leans forward. The gravity action line led down from the center of gravity goes beyond the bottom of the foot, so the person falls forward. However, before this fall action is realized, the foot in the air soon falls on the ground in front of the gravity action line led down from the center of gravity, making the action line return to the area between the two feet, so the foot falls The lost balance was restored.

Source: @alessandro_peki

Sleeve Tattoo is a tattoo or a collection of tattoos designed to cover the arm. Depending on your preference, the sleeves may be full, in which case they extend from the shoulder to the wrist, or they can be half or three-quarters of the sleeves. With the tattoo more and more accepted by the society, sleeve tattoo has become more and more prominent. Some famous artists and artists like Sleeve Tattoo very much.

A complete Sleeve Tattoo may need to sit several times, and the design methods of Sleeve Tattoo are different for several hours each time. In some cases, the tattooer works with an artist to create a unified look and theme for the sleeves. The artist works on the sleeve in stages to create a very streamlined work. In other cases, the artist may add bits and pieces to the sleeve to work with the client to create the desired look.

Some people also like to show the works of various artists on their sleeves. The sleeve tattoo can cover part or all of the arm. Like other tattoos, the style and content of sleeve tattoos are very diverse. Some people use sleeves to commemorate specific events or people in their lives. In this case, there may be some personal significant items on the tattoos. In other cases, sleeves celebrate art from a particular culture in a unified artistic style, such as Japan or Tahiti. Other people just like to put on beautiful clothes, colorful art display, when they see what they like or meet talented artists, they will tattoo their sleeves.

Source: @__jayyj__

Now more and more people begin to tattoo angel wings on their bodies. Among them, even some stars like angel wings tattoo, especially the little angel wings tattoo. We see more angel wing patterns, such as a male or female angel, unfolding the wing pattern. So, what’s the meaning of this angel wing tattoo?

Angels convey God’s will to people. On the tattoo, they represent the symbol of protection, prayer or peace. The most famous Archangel Michael is the angel hero fighting against Satan. It’s a soldier with a lot of things to do. But there is also the angel Lucifer who has fallen into the devil and become the so-called fallen angel. Tattooing wings seems to enable people to have positive energy, but the wings of angels and demons are different in design. Sometimes tattooists will also use two different types of wings to balance positive and negative energy.

Angel wing tattoo represents freedom and romance, is the angel’s wings. Wing tattoo has always been a popular tattoo pattern among tattoo lovers. Angel wing tattoo means purity, is an angel, is a symbol of freedom, also has the moral of protection. Most of the wing tattoos have pure white feathers, which are considered to be the wings of angels.

Angel wings bring good news to human beings, and angel wings tattoo naturally means good, but this single tattoo can not meet the needs of modern tattoo lovers, so angel wings are often combined with other patterns to form more meaningful tattoos. The wings of angels are mostly feathery, and the corners are very round. The wings of demons are bat like and have sharp spines around the corner. Or there are some devil wings with bone wings.

Source: @animalisticbones

Airship is a kind of lighter than air aircraft. The biggest difference between airship and hot air balloon is that it has the device to propel and control the flight state. The airship is composed of a large streamlined hull, a pod under the hull, a stern for stability control and a propulsion device.

The air bag of the hull is filled with buoyant gas (hydrogen or helium) which is less dense than air, so as to generate buoyancy and lift the airship. The pods are for people to ride and load cargo. The tail surface is used to control and maintain the stability of course and pitch. Large civil airships can also be used for transportation, entertainment, disaster relief, film and television shooting, scientific experiments and so on. For example, in the event of a natural disaster, if the communication is interrupted, a buoy can be quickly launched. By carrying the communication transponder through the buoy, the mobile communication recovery of the whole disaster area can be completed in a very short time.

Source: @absheroriginal

Biplane is an aircraft with two wings arranged side by side. Its upper and lower wings are connected into a load-bearing whole by pillars and cables to form a space truss structure. The aircraft with two wings in front and back configuration is called tandem wing aircraft. In the early stage of aircraft development, the engine power was low and the weight was large, and the materials used to build the airframe were mostly wood and Mongolian cloth. In order to solve the problem of lift off, a large wing area is needed to generate enough lift at low speed. The biplane has two wings, and the total wing area is large. In modern aircraft, except for the small aircraft with special requirements for payload and low speed performance, biplane is rare.

An aircraft with two wings arranged side by side. The aircraft with two wings in front and back configuration is called tandem wing aircraft. The upper and lower wings of the biplane are connected with struts and cables to form a load-bearing whole, forming a space truss structure. Biplane is an old style aircraft. In the early stage of aircraft development, the engine power was low and the weight was large, and the materials used to build the airframe were mostly wood and Mongolian cloth. In order to solve the problem of lift off, a large wing area is needed to generate enough lift at low speed. The biplane has two wings, and the total wing area is large.

Source: @_tattoobar_