Doppler effect videos (i.e., Doppler effect videos):
1. Fire Engine siren demonstrates the Doppler Effect | 0:18: Good and has sound. Short enough for classroom.
2. The Doppler Effect: what does motion do to waves? | 3:02: OK animation, but deplorably it conflates Doppler effect and the cosmological redshift which are different, though related, effects in the opinion of yours truly. Too long for the classroom.
3. SONIC BOOMS & JETS | Best Compilation | 3:26: No chit and chat, just sonic booms. The first sonic boom shows the vapor cone caused by the condensation of water vapor just as the jet goes transonic. Vapor cone do NOT always form. Just show first 60 seconds or so in the classroom.
4. How to Crack a Whip | 2:21: When a whip is cracked, a wave packet accelerates down the whip and breaches the sound speed (340 m/s at sea level at 15° C: Wikipedia: Speed of Sound: Tables) and creates a small sonic boom (see Wikipedia: Whip: Cracking; Wikipedia: Whipcracking). Whips were the first human human artifact to breach the sound barrier (see Wikipedia: Whip: Cracking).
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