एक वस्तु को बिंदु A से क्षैतिज के साथ \(60^{\circ}\) के कोण पर गतिज ऊर्जा K के साथ प्रक्षेपित किया जाता है। वायु घर्षण की अनुपस्थिति में, बिंदु B और C पर गतिज ऊर्जाओं में अंतर तथा बिंदु A पर गतिज ऊर्जा का अनुपात (आकृति देखें) है:

A 1 : 2
B 2 : 3
C 1 : 4
D 3 : 4

Verified Solution

Answer & Solution

Correct Answer

(D) 3 : 4

Step-by-step Solution

Detailed explanation

\( (KE)_{A}=K=\frac{1}{2}mu^{2} \) \(( KE )_{ B }=\frac{ K }{4}=\frac{1}{2} m\left(\frac{ u }{2}\right)^2=\frac{ K }{4}\left( u _{ B }= u \cos 60^{\circ}=\frac{ u }{2}\right)\) \( (KE)_{C}=K \) अनुपात \(= \frac{K-K/4}{K} \) \(=\frac{3 K / 4}{K}=\frac{3}{4}\)

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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