Real-world examples of wave speed for Grade 7.

📚 Quick Study Guide

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• Wave Speed: The distance a wave travels in a certain amount of time.
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• Formula: Wave Speed ($v$) = Frequency ($f$) x Wavelength ($\lambda$), or $v = f\lambda$. Sometimes you'll see it as Speed = Distance / Time.
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• Units: Wave speed is usually measured in meters per second (m/s).
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• Frequency: How many waves pass a point in one second (Hertz or Hz).
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• Wavelength: The distance between two corresponding points on a wave (e.g., crest to crest).
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• Factors Affecting Wave Speed: The medium (e.g., air, water, solid) through which the wave travels and its properties (e.g., temperature, density).

🧪 Practice Quiz

1. What is the formula for calculating wave speed?
   1. $v = f + \lambda$
   2. $v = f \times \lambda$
   3. $v = \frac{f}{\lambda}$
   4. $v = \lambda - f$
2. A wave has a frequency of 5 Hz and a wavelength of 2 meters. What is its speed?
   1. 2.5 m/s
   2. 10 m/s
   3. 7 m/s
   4. 0.4 m/s
3. Sound waves travel faster in which medium?
   1. Air
   2. Water
   3. Vacuum
   4. Solid (e.g., steel)
4. If a wave travels 20 meters in 4 seconds, what is its speed?
   1. 5 m/s
   2. 80 m/s
   3. 16 m/s
   4. 24 m/s
5. What unit is typically used to measure wave speed?
   1. Hertz (Hz)
   2. Meters (m)
   3. Meters per second (m/s)
   4. Seconds (s)
6. A wave's speed increases, but its frequency stays the same. What happens to its wavelength?
   1. It decreases.
   2. It stays the same.
   3. It increases.
   4. It becomes zero.
7. Imagine you see lightning and then hear thunder 6 seconds later. If the speed of sound is approximately 343 m/s, how far away was the lightning?
   1. 57.17 meters
   2. 2058 meters
   3. 349 meters
   4. 600 meters