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NEET
Exam
NEET
Subject
Physics
Chapter
Motion in Two Dimensions

NEET · Physics · Motion in Two Dimensions

Assertion : For projection angle ( ^ -1 (4)), the horizontal and...

Assertion : For projection angle (\tan ^{-1}(4)), the horizontal and maximum height of a projectile are equal. Reason : The maximum range of projectile is directly proportional to square of velocity and inversely proportional to acceleration due to gravity.

Options

  1. AIf both Assertion and Reason are correct and Reason is the correct explanation of Assertion.
  2. BIf both Assertion and Reason are true but Reason is not the correct explanation of Assertion.
  3. CIf Assertion is true but Reason is false.
  4. DIf Assertion is false but Reason is true.

Correct answer

B. If both Assertion and Reason are true but Reason is not the correct explanation of Assertion.

Step-by-step solution

- Assertion: The assertion states that for a projection angle of (\tan ^{-1}(4)), the horizontal range (RR) and the maximum height (HH) are equal. This statement is true. The formulas for range and maximum height are: (R=\frac{u^2 \sin (2 \theta)}{g} \text{ and } H=\frac{u^2 \sin ^2 \theta}{2 g}) For R=HR=H, we set the equations equal to each other: (u2sin⁡(2θ)g=u2sin⁡2θ2g2sin⁡θcos⁡θ=sin⁡2θ24cos⁡θ=sin⁡θsin⁡θcos⁡θ=4tan⁡θ=4θ=tan⁡−1(4)\begin{aligned} & \frac{u^2 \sin (2 \theta)}{g}=\frac{u^2 \sin ^2 \theta}{2 g} \\ & 2 \sin \theta \cos \theta=\frac{\sin ^2 \theta}{2} \\ & 4 \cos \theta=\sin \theta \\ & \frac{\sin \theta}{\cos \theta}=4 \\ & \tan \theta=4 \\ & \theta=\tan ^{-1}(4) \end{aligned}) This confirms the assertion is correct. - Reason: The reason states that the maximum range of a projectile is directly proportional to the square of the velocity and inversely proportional to the acceleration due to gravity. The formula for the maximum range is (R_{\text{max }}=\frac{u^2}{g}). This is obtained when the projection angle (\theta=45^{\circ}). This formula shows that (R_{\text{max }}) is directly proportional to the square of the initial velocity (u2u^2) and inversely proportional to the acceleration due to gravity (gg). Thus, the reason is true. Conclusion Both the Assertion and the Reason are correct. However, the reason discusses the maximum range and its dependencies, while the assertion is about the condition for any range to be equal to the height. The reason, therefore, is a correct statement about projectile motion but does not explain the specific condition in the assertion. This corresponds to option (2).
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