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Frequency range of hearing is different and the range decreases with age, but usually the highest frequency of human hearing is about 20 or 25 kHz is considered. The opposite of the waves or subsonic waves (subsonic), which has a frequency below the lower limit of human hearing frequencies (approximately دانلودها 20 Hz) are. The term ultrasound, ultrasound should (in English: Supersonic) is moving faster than the speed of sound used, confused.
Ultrasonic testing is one of the NDT methods. In this method, high-frequency and low-amplitude sound waves are sent into the piece. These waves then reflect the impact of any disruption. The scope and timing of the return of the waves can be characterized by fragmentation realized. Applications of this method can be used to measure thickness and detect flaws in components named. دانلودها One major advantage of this method is its ability دانلودها to detect very small defects due to the high frequency of the waves and therefore the wavelength is very small. Security applications
Ships and the Sea of the system to control the depth of the sea and to the existence of objects in the water. Ultrasonic radars are used to infer the existence of flying objects. See the subsonic
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What characteristics of sound and sound barrier and because it requires strength and elasticity and ability to pass a lot. Sound, in normal conditions (temperature, pressure and normal) at a speed of 340 m above sea level Sanyhast دانلودها the speed, دانلودها pressure and air density decreases with increasing altitude دانلودها and decreased at higher altitudes, speed of sound intervals less contemporary. It may be that the sound blows through the air molecules together and transfer energy through space and the number of molecules in a given volume greater than one, energy transfer to the speed of sound soon as possible on accepted moving-As velocity of sound In most liquids and solids are much more fluid and air from the air, the equivalent of 6,000 miles per hour.
The resulting increase in plant height, number of molecules in a given volume of space is reduced and the sound traveled at lower speeds. Sound walls, and physical objects are not visible, but because it needs to be very high traverse speed of sound is very good motor and aerodynamic, so it is considered a barrier to higher speeds, and the sound barrier, refer to. Mach number, in fact, the relative speed of the object is a bird or a plane to the speed of sound in honor of the Austrian scientist who first such scale to be considered it as "Mach named. The Mach number, quantity varies دانلودها depending on the air properties such as temperature and pressure changes and reductions or increases. Cause the sound barrier
Shock waves (Shockwaves) are in fact the main factor causing the sound barrier. Shock waves, sudden changes in pressure and temperature of a layer of air that can be moved to other layers of space travel as a wave. To better understand this, when a stone is thrown in water, waves occur in water that is moving outwards. These waves, thus increasing the speed or force applied to a layer of water molecules that are able to move to other layers, and shock waves, the same waves in the water, but the other liquid instead of water in the air formed. دانلودها Critical Mach number
The rate at which at least one of the plane surfaces of the speed of sound is reached, although this is not true about the airplane itself, the critical Mach number (Critical دانلودها Mach Number) say. Critical Mach number can be as fast as the speed of the drag curve is upward, as defined. At this speed, the aircraft commands began to not answering the right-wing state like slamming on the impact دانلودها waves caused by passing through the sound barrier, aircraft orders are to its natural state. Effects broke the sound barrier
Beats by plane waves at the speed of sound, is very powerful, as if passing to fly an airplane close to the ground دانلودها and the wall of sound, shock waves with the best power-to-ground objects such as glass houses hit the buildings and break them, or If a person is directly exposed to shock waves, the likelihood دانلودها of hearing loss and it is a ruptured eardrum.
The shock waves of bombs and other weapons used. Bombs with a sudden دانلودها increase in temperature and pressure in the layers of air, shock waves are created that are transmitted through the air and breaking windows and destroying the wall. If a person is relatively close in distance in the air and the vacuum of empty space, not even close to a ten-ton bombs stopped, the assumption detonate bombs will not hurt him, because air does not blow waves to transmit. دانلودها
Due to the shock wave at the speed of sound speed, the pilots try to fly only a short time and at such speeds Transvnyk soon pass the sound barrier, flying at this speed because the motor overload Consequently the increase in super fuel followed.
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