Question

Speed of sound in sea water at \(25^\circ\text{C}\) is :

• A. 1531 m/s
• B. 1533 m/s
• C. 1536 m/s
• D. 1498 m/s

Hint:

The speed of sound depends on the medium.
Air (\(20^\circ\text{C}\)): \(\sim 343 \text{ m/s}\)
Fresh Water (\(20^\circ\text{C}\)): \(\sim 1482 \text{ m/s}\)
Sea Water: Generally faster than in fresh water due to salinity. For seawater at \(25^\circ\text{C}\), a typical value is around {1531 m/s}. This is a factual value often used in physics and oceanography.

Answer 1

The Correct Option is A

Concept: The speed of sound varies depending on the medium through which it travels and factors like temperature, pressure, and salinity (for water). Sound generally travels faster in liquids and solids than in gases. Step 1: Factors Affecting Speed of Sound in Water In water, the speed of sound is primarily affected by:
Temperature: Speed increases with increasing temperature.
Salinity (salt content): Speed increases with increasing salinity. This is particularly relevant for seawater.
Pressure (Depth): Speed increases with increasing pressure (and thus depth). Step 2: Typical Values for Speed of Sound
In Air (at \(20^\circ\text{C}\)): Approximately \(343 \text{ m/s}\).
In Fresh Water (at \(20^\circ\text{C}\)): Approximately \(1482 \text{ m/s}\).
In Sea Water: Due to salinity and typically higher pressure at depth, the speed of sound in seawater is generally higher than in fresh water. Step 3: Speed of Sound in Seawater at \(25^\circ\text{C}\) The speed of sound in seawater is a standard value that depends on these factors. At a temperature of \(25^\circ\text{C}\), standard salinity (e.g., 35 parts per thousand), and atmospheric pressure (surface), the speed of sound is approximately \(1530 - 1535 \text{ m/s}\). More precise empirical formulas (like those by Medwin or Mackenzie) exist for calculating it. A commonly cited value for "typical" surface seawater at \(25^\circ\text{C}\) is around \(1531 \text{ m/s}\) to \(1533 \text{ m/s}\). Step 4: Comparing with the options
(1) 1531 m/s: This value is well within the expected range for seawater at \(25^\circ\text{C}\) and is a commonly referenced standard value.
(2) 1533 m/s: Also a very plausible value, very close to 1531 m/s.
(3) 1536 m/s: Slightly higher, but could be possible under specific salinity/pressure.
(4) 1498 m/s: This value is closer to the speed of sound in fresh water at around \(25^\circ\text{C}\) (or slightly warmer fresh water). Seawater speed is generally higher. Given that option (1) 1531 m/s is circled and is a widely accepted reference value for the speed of sound in seawater under conditions approximating \(25^\circ\text{C}\) and standard salinity at the surface, this is the most likely correct answer. Small variations exist based on exact salinity and pressure.