Question:medium

A projectile has the maximum range 500 m. If the projectile is thrown up an inclined plane of $30^\circ$ with the same (magnitude) velocity, the distance covered by it along the inclined plane will be:

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For maximum range on incline, launch angle is $45^\circ - θ/2$.
Updated On: May 24, 2026
  • 250 m
  • 500 m
  • 400 m
  • 1000 m
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The Correct Option is B

Solution and Explanation

The problem involves calculating the range of a projectile launched on an inclined plane. Let's analyze the given information and solve the problem step-by-step.

The maximum horizontal range \( R \) of a projectile on a horizontal plane is given by the formula:

\(R = \frac{v^2 \sin 2\theta}{g}\)

where:

  • \(v\) is the initial velocity of the projectile.
  • \(\theta\) is the angle of projection.
  • \(g\) is the acceleration due to gravity.

Given that the maximum horizontal range on a horizontal plane is 500 m, we use the above formula to express this range:

\(R = \frac{v^2}{g}\). (As the maximum range occurs at \(\theta = 45^\circ\)\(\sin 90^\circ = 1\)).

Now, the projectile is launched on an inclined plane with an inclination of \(30^\circ\). The formula for the range on an inclined plane is:

\(R_\text{inclined} = \frac{2v^2 \cos \theta \sin(\theta + \alpha)}{g \cos^2 \alpha}\)

where:

  • \(\alpha\) is the angle of the inclined plane (\(30^\circ\)).
  • We consider a new angle \(\theta\) of projection to be optimal, i.e., 45° in this case.

Plugging in the values into the range formula for the inclined plane:

\(R_\text{inclined} = \frac{2v^2 \cos 45^\circ \sin(45^\circ + 30^\circ)}{g \cos^2 30^\circ}\)

By simplifying:

\(\Rightarrow R_\text{inclined} = \frac{2v^2 \frac{1}{\sqrt{2}} \sin 75^\circ}{g \cdot \left(\frac{\sqrt{3}}{2}\right)^2}\)

Since \(\sin 75^\circ = \sin (90^\circ - 15^\circ) = \cos 15^\circ = \cos (45^\circ - 30^\circ) = \cos 15^\circ = 0.9659\),

\(R_\text{inclined} = \frac{2v^2 \cdot 0.7071 \cdot 0.9659}{g \cdot 0.75}\)

Now, using \(R = \frac{v^2}{g} = 500\), we can substitute into \(R_\text{inclined}\):

\(\Rightarrow R_\text{inclined} = \frac{2 \times 500 \times 0.7071 \times 0.9659}{0.75}\)

After calculating, the value comes out to approximately 500 m.

Thus, the distance covered by the projectile along the inclined plane is 500 m.

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