Lesson 4 of 6 · Sound
Lesson⭐ 30 XPEchoes, Sonar and Ultrasound
Echoes, Sonar and Ultrasound.
🎯 Your mission
Master the concept. Use it tomorrow.
⚡ The twist
Nature loves to surprise the careful watcher.
Mind = Blown
🔬 The more you look, the more nature shows you.
Make a hypothesis first
Before you start: write down what you think will happen, and why.
What You'll Learn
Sound reflecting off a surface returns as an echo. Time it and you can find distance, because distance equals speed times half the round-trip time. Ships use this as sonar, and medicine uses ultrasound above 20 kHz to image inside the body without ionising radiation.
Key Words
Tap a word to see its definition.
Steps
Read the explanation above and note the two key terms before you start.
Calculate the depth of water under a boat given an echo return time of 0.16 s and a sound speed of 1,500 m/s. Then design a labelled diagram of how an ultrasound scan builds an image from reflections at tissue boundaries.
Record what actually happened, including anything that did not match what you expected.
Write a conclusion that answers the question this lesson opened with, and state your uncertainty.
Check Your Understanding
Question 1
1 of 2A sonar pulse returns after 0.16 s in water at 1,500 m/s. The depth is:
Where you see this in real life
This shows up in your everyday life more than you'd think.
Stretch Challenge
Try this in real life this week.
Try one experiment in real life this week — even a tiny one.
For the dinner table
“What's the most surprising thing you learned today?”
Next Smart Experiment
We'll pick an experiment that matches exactly how you're thinking right now.
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Ready?
Echoes, Sonar and Ultrasound
Master the concept. Use it tomorrow.
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