એક લોલકના દોલકને સમક્ષિતિજ સ્થિતિ આગળથી મુક્ત કરવામાં આવે છે, લોલકની લંબાઈ \(10 \mathrm{~m}\) છે. જો દોલકની \(10 \%\) ઊર્જા એ હવાના અવરોધની સામે વેડફાતી હોય તો તે જ્યારે નીચેના ન્યૂનતમ બિંદુ આગળ પહોચે ત્યારે દોલક ની ઝડ૫ _______ થશે.[\({ g: } 10 \mathrm{~ms}^{-2}\) નો ઉપયોગ કરો]

A \(6 \sqrt{5} \mathrm{~ms}^{-1}\)
B \(5 \sqrt{6} \mathrm{~ms}^{-1}\)
C \(5 \sqrt{5} \mathrm{~ms}^{-1}\)
D \(2 \sqrt{5} \mathrm{~ms}^{-1}\)

Verified Solution

Answer & Solution

Correct Answer

(A) \(6 \sqrt{5} \mathrm{~ms}^{-1}\)

Step-by-step Solution

Detailed explanation

\( \ell=10 \mathrm{~m} \) \( \text { Initial energy }=\mathrm{mg} \ell \) \( \text { So, } \frac{9}{10} \mathrm{mg} \ell=\frac{1}{2} \mathrm{mv}^2 \) \( \Rightarrow \frac{9}{10} \times 10 \times 10=\frac{1}{2} \mathrm{v}^2 \) \( \mathrm{v}^2=180 \)…

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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