Describe, using diagrams, the difference between transverse waves and longitudinal waves - Leaving Cert Physics - Question 8 - 2006

Sound travels through a medium in the form of waves, where energy is transferred from particle to particle. In solids, particles are closely packed and vibrate, allowing sound waves to travel efficiently. In liquids and gases, sound travels slower due to increased distance between particles, which leads to less efficient energy transfer. Energy passes through vibrations of particles, facilitating the movement of sound waves.

You can conduct an experiment using a vacuum jar and a bell. Place the bell inside a sealed jar and begin to pump out air. As the air is removed, the sound produced by the bell decreases until it is no longer audible, demonstrating that sound requires a medium (air) to travel.

The time taken for the pulse to reach the seabed is 0.2 s, as the total time for the pulse to travel to the seabed and back is 0.4 s. Therefore, when divided by 2, we have:

Using the formula: $ext{Distance} = ext{Speed} imes ext{Time}$ we can find the depth of the water. The pulse takes 0.2 s to reach the seabed. So the depth is: $ext{Depth} = 1500 ext{ m/s} imes 0.2 ext{ s} = 300 ext{ m}$.

Using the wave equation: $ext{Wave Speed} = ext{Frequency} imes ext{Wavelength}$ we rearrange to find the wavelength: $ext{Wavelength} = \frac{\text{Wave Speed}}{\text{Frequency}}$ Substituting the known values: $\text{Wavelength} = \frac{1500 ext{ m/s}}{50 000 ext{ Hz}} = 0.03 ext{ m}$.

The speed of sound is greater in water than in air primarily because particles in water are closer together, allowing for quicker vibrations and energy transfer. Additionally, water has a higher density compared to air, which facilitates the propagation of sound waves more efficiently.