એક એંજિન પર્વત પર અચળ વેગથી ચડે છે.જ્યારે તે \(0.9\, km\) અંતરે હોય ત્યારે તે હોર્ન વગાડે છે જેનો પડઘો ડ્રાઇવરને \(5\, seconds\) પછી સંભળાય છે. જો હવામાં ધ્વનિનો વેગ \(330\, m/s\) હોય તો એંજિનનો વેગ \(m/s\) માં કેટલો હશે?

A \(32\)
B \(27.5\)
C \(60\)
D \(30\)

Verified Solution

Answer & Solution

Correct Answer

(D) \(30\)

Step-by-step Solution

Detailed explanation

Let after 5 sec engine at point \(C\) \(t=\frac{A B}{330}+\frac{B C}{330}\) \(5=\frac{0.9 \times 1000}{330}+\frac{\mathrm{BC}}{330}\) \(\therefore \mathrm{BC}=750 \mathrm{m}\) Distance travelled by engine in \(5\, sec\) \(=900 \mathrm{m}-750 \mathrm{m}=150 \mathrm{m}\) Therefore…

Apply the relevant identity from the chapter and substitute the values established in the previous step, keeping the original constraint in view.

Use the simplified expression to isolate the unknown, then plug the result back into the question setup to confirm the working is internally consistent.

Cross-check against a boundary or limiting case. Both the dimensional balance and the qualitative behaviour at the extreme should agree with the candidate answer.

Combine the steps above to identify the correct option. The remaining choices each fail at least one of the consistency, dimensional, or boundary checks.

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