Question

How do i do this question？just number 5

Answer 1

5 a)

Start by arranging the materials by the sonic speed and then their physical state:

• $4600 \; \text{m} \cdot \text{s}^{-1}$- Copper (solid)
• $4500 \; \text{m} \cdot \text{s}^{-1}$- Glass (solid)
• $4000 \; \text{m} \cdot \text{s}^{-1}$- Wood (solid)

• $1500 \; \text{m} \cdot \text{s}^{-1}$- Sea Water (liquid)
• $1200 \; \text{m} \cdot \text{s}^{-1}$- Acetone (liquid)
• $1100 \; \text{m} \cdot \text{s}^{-1}$- Alcohol (liquid)

• $972 \; \text{m} \cdot \text{s}^{-1}$- Helium (gas)
• $267 \; \text{m} \cdot \text{s}^{-1}$- Carbon dioxide (gas)

What trend do you identify from these data? Here's what I've got:

$\text{Sonic Speed}: \text{solid} > \text{liquid} > \text{gas}$

5 b)

The way microscopic particles are arranged in a substance helps distinguish between different physical states:

• Particles in a solid are held tightly in place with small separation in between; it's hard for particles in a solid to move past one another; solids therefore have shapes that persists over time.
• Particles in a gas are highly mobile- they keep moving AT ALL TIMES. There are large separations between individual particles and therefore gases tend to show no definite shape or volume.
• The arrangement of particles in a liquid is located somewhere in between that of solids and gases. The exact configuration is dependent on the nature of the liquid- for example, molecules in maple syrup are held way closer to each other than those in distilled water are.

Sound travels as a longitudinal wave. As a sound wave passes through a medium, individual particles become excited and gain energy; as they run into others they transfer their energy to the next particle; the sound wave thus propagate across the medium. With a lower average distance between individual particles this action can proceed at a greater rate in average solids than in average liquids, and in average liquids than in average gases. Hence the trend.