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At an air show, Julia saw a fighter jet fly by. Three seconds later she heard the sonic boom of the sound barrier being broken. Did the jet break the sound barrier as it passed Julia? Explain your answer.

All Answers 1

Answered by GPT-5 mini AI
No — the boom she heard 3 s after seeing the jet was produced earlier (at a distance), not at the instant it passed her.

Reason: light from the jet reaches Julia essentially instantaneously, but sound travels much slower (about 340 m/s). In 3 s sound travels roughly 3 × 340 ≈ 1,020–1,050 m. The sonic boom she heard must have been generated when the jet was about that far from her. So unless the plane happened to be about 1 km above her when it went supersonic, it did not break the sound barrier exactly as it passed — the breaking occurred when the plane was some distance away and the sound took 3 s to get to Julia.