Railway Science (Physics-Sound) (Part-II)

Speed of sound in different media at 25°C : Nickel - 6040 m/s, Steel - 5960 m/s, Water (Sea) - 1531 m/s, Water (distilled) - 1498 m/s, Hydrogen - 1284 m/s, Air - 346 m/s, Oxygen - 316 m/s.

Speed of sound in Solid state at 25 ºC ( Substance and Speed in m/s): Aluminium (6420), Nickel (6040), Steel (5960), Iron (5950), Brass (4700), Glass (Flint) (3980).

Speed of sound in Aluminium (Al) is around 6420 m/s at 25°C. Sound is a mechanical wave. Sound waves travel the slowest through gases and fastest through solids. Sound waves are longitudinal waves. The speed of sound in air is 343 m/s at 20 °C. The normal frequency of the sound heard by the human ear is 20 Hz to 20 kHz. Sound wave above 20 kHz - Ultrasonic Sound. Less than 20 Hz sound waves - Infrared. The relation between the speed of sound, its frequency and wavelength is v(velocity) = f(frequency) x λ(wavelength).

Speed of sound changes in a medium at 25°C: Nickel- 6040 m/s, Steel- 5960m/s, Aluminium- 6420 m/s, Water (Sea)- 1531 m/s, Water (distilled)- 1498 m/s, Hydrogen- 1284 m/s, Air- 346 m/s, Oxygen- 316 m/s.

The speed of sound at 25°C in different mediums: Aluminum - 6420 m/s, iron - 5950 m/s, Brass - 4700 m/s, Sea water - 1531 m/s, Distilled water - 1498 m/s, hydrogen - 1284 m/s, etc. The speed of sound in air is 331 m/s at 0°C and 344 at 22°C.

Loudness is how loud or soft a sound seems, determined by the intensity of sound waves, measured in decibels (dB). Frequency, measured in hertz (Hz), is the pitch of sound. The audible range for humans is 20 Hz to 20 kHz.

When an object vibrates, it sets the surrounding air molecules in motion, creating waves of pressure variations that travel outwards. When these waves reach our ears then it is interpreted as sound.

Sound propagates through a medium at a finite speed.The speed of sound depends on the properties of the medium through which it travels. Speed (in m/s) of sound in different media at 25°C: Solids - Aluminium (6420), Nickel (6040), Steel (5960), Iron (5950), Brass (4700), Glass (3980); Liquids - Sea water (1531), Distilled water (1498), Ethanol (1207), Methanol (1103); Gases - Hydrogen (1284), Helium (965), Air (346), Oxygen (316), Sulfur dioxide (213).

Speed of sound in different media at 25ºC: In Solids - Aluminium (6420 m/s), Nickel (6040 m/s), Brass (4700 m/s); In Liquids - Sea water (1531m/s), Methanol (1103 m/s); In Gases - Air (346 m/s), Oxygen (316 m/s), and Sulphur dioxide (213 m/s).

This porous material is commonly used in auditoriums because it effectively
absorbs sound waves, reducing resonance and improving clarity of sound. Other sound-absorbing materials used include fabric panels, acoustic tiles, and carpeting.