Class NEET 2026 ALL Q #1927
COMPETENCY BASED
APPLY
4 Marks 2026 NTA-RE-NEET-2026 MCQ SINGLE
A car travels on a circular racetrack of radius 50 m, which is banked at an angle $\theta$. If the car travels at a speed $10~ms^{-1}$, then the wear and tear on its tyres is minimum. Taking the acceleration due to gravity to be $10~ms^{-2}$, the value of $\theta$ is:
(A) $\tan^{-1}(2\sqrt{3})$
(B) $\tan^{-1}(\frac{1}{5})$
(C) $\tan^{-1}(\frac{2}{5})$
(D) $\tan^{-1}(\sqrt{3}/2)$
Correct Answer: B

AI Tutor Explanation

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Detailed Solution

Step 1: Identify the Physical Condition

For a car moving on a banked circular track, the wear and tear on the tyres is minimum when the frictional force is zero. This occurs when the centripetal force is provided entirely by the horizontal component of the normal reaction.

Step 2: Apply the Banking Formula

The condition for safe turning without friction is given by the formula:

$$ \tan(\theta) = \frac{v^2}{rg} $$

Where $v$ is the velocity, $r$ is the radius of the track, and $g$ is the acceleration due to gravity.

Step 3: Substitute the Given Values

Given: $v = 10 \, ms^{-1}$, $r = 50 \, m$, and $g = 10 \, ms^{-2}$.

$$ \tan(\theta) = \frac{10^2}{50 \times 10} $$ $$ \tan(\theta) = \frac{100}{500} $$ $$ \tan(\theta) = \frac{1}{5} $$

Step 4: Calculate the Angle

Taking the inverse tangent on both sides:

$$ \theta = \tan^{-1}\left(\frac{1}{5}\right) $$

Final Answer: \tan^{-1}(\frac{1}{5})

AI Suggestion: Option B

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Pedagogical Audit
Bloom's Analysis: This is an APPLY question because the student must identify the correct physical principle (banking of roads) and apply the derived formula to a specific numerical scenario.
Knowledge Dimension: PROCEDURAL
Justification: The question requires the student to follow a specific sequence of steps involving the application of the centripetal force equation to solve for an unknown variable.
Syllabus Audit: In the context of NEET, this is classified as COMPETENCY. This question tests the student's ability to relate theoretical concepts of circular motion to real-world engineering applications like road banking.