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JEE Main 2023 (29 Jan, Shift 1) · Conservation of Energy

Conservation of Energy question from JEE Main 2023 (29 Jan, Shift 1)

Q16JEE Main 2023 · 29 JAN · SHIFT 1Easy

Conservation of Energy

A stone is projected at angle 30∘30^\circ to the horizontal. The ratio of kinetic energy of the stone at point of projection to its kinetic energy at the highest point of flight will be -

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Answer: (c)

  1. At the top, Ktop=Kcos⁡2θK_{top} = K\cos^2\theta, so KKtop=1cos⁡230∘\frac{K}{K_{top}} = \frac{1}{\cos^2 30^\circ}.
  2. cos⁡230∘=34⇒KKtop=43\cos^2 30^\circ = \frac{3}{4} \Rightarrow \frac{K}{K_{top}} = \frac{4}{3}
  3. So the answer is (c) 4:34:3.
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