Doppler Effect & Relative Motion — Drills · Grade 12 Science
Chapter: Waves, Sound & OpticsWhat these drills covers
By the end of Doppler Effect & Relative Motion you should be able to:
- I can predict sound pitch changes with specified source/observer motion.
- I can choose a sound formula and distinguish it from electromagnetic shift models.
2 questions, numeric and written answer, each with a worked explanation.
Vocabulary used: Doppler shift, redshift.
Problem 1
500 Hz source approaches at 10 m/s; v=350 m/s. Find fobs.
Hints
Write the relationship first; substitute with consistent units.
Answer and explanation
514.71 Hz
500×350/340≈514.71.
Problem 2
Does source motion make sound travel faster through stationary air?
Answer and explanation
No; it changes front spacing, while medium properties largely determine speed.
Response criteria
- State a scientifically accurate conclusion.
- Show the calculation or mechanism that supports it.
- Include units, conditions, or limits where relevant.