Sound is a mechanical wave that requires a material medium (solid, liquid, or gas) to propagate. It travels by vibrating the particles of the medium. In a vacuum, there are no particles to transmit these vibrations; therefore, sound cannot travel through a vacuum. This is why space is silent.

The speed of sound in a gas is given by v = sqrt(gamma * P / rho). Moist air contains water vapor, which has a lower molar mass than nitrogen and oxygen. Consequently, moist air is less dense than dry air at the same temperature and pressure. Since velocity is inversely proportional to the square root of density, sound travels faster in less dense moist air.

Supersonic speed refers to any speed that is faster than the speed of sound (Mach 1). Objects traveling at these speeds generate shock waves as they move through the medium.

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The speed of sound depends on the elasticity and density of the medium. Sound travels faster in solids than in liquids or gases because the particles in solids are more tightly packed, allowing for more efficient transmission of mechanical vibrations. Among the choices provided, iron is a solid with a high elastic modulus, resulting in a higher speed of sound compared to water (liquid) or air (gas).

When a drumhead is struck, it vibrates rapidly, causing the surrounding air molecules to oscillate. These oscillations create pressure waves that propagate through the medium as sound energy, which is perceived by the human ear as sound.

The speed of sound is determined by the physical properties of the medium, specifically its elasticity (bulk modulus) and density. Sound travels faster in denser or more rigid materials, as these properties affect how efficiently mechanical energy is transferred between particles.

The frequency (f) of a wave is the reciprocal of its time period (T), expressed by the formula f = 1/T. Given T = 0.01 seconds, the calculation is f = 1 / 0.01 = 100 Hz. Thus, the wave completes 100 cycles per second.

The speed of sound is proportional to the square root of temperature (v ∝ √T). Since temperature decreases with altitude in the troposphere, the speed of sound is lower at 15 km than at sea level. Thus, Mach 1 (the speed of sound) is actually slower at high altitude.

Sound travels fastest in solids because the particles in a solid are more closely packed together than in liquids or gases. This high density and strong intermolecular forces allow mechanical vibrations to be transmitted more efficiently and rapidly between adjacent particles.