Question

A solid cone is revolving inside the circle as shown. Parallel sunlight at 45 degrees to the ground is creating the shadow of the cone. Which option represents the total region covered by the shadow for one complete revolution when seen from the top?

• A. A
• B. B
• C. C
• D. D

Hint:

When analyzing shadows caused by revolving objects, consider the angle of light and the object's geometry to predict the shadow's coverage.

Answer 1

The Correct Option is B

1. Analysis of the Problem:
- The shadow of the cone is determined by the cone's movement during its revolution and the angle of sunlight.
- As the cone revolves, the shadow extends outward and overlaps during the revolution due to the circular motion and the 45-degree angle of sunlight.
2. Pattern of the Shadow:
- The shadow will cover an elliptical region on the ground, and its shape will be influenced by the 45-degree angle of sunlight, resulting in overlapping areas as the cone completes its revolution.
3. Options Analysis:
- Option A: Shows a simple circular shadow, which is incorrect as it does not account for the 45-degree angle of sunlight.
- Option B: Correctly represents the overlapping elliptical shadow resulting from the cone’s revolution and the sunlight angle.
- Option C: Depicts an elongated shape inconsistent with the motion of the cone.
- Option D: Shows a shape that does not accurately reflect the total shadow region during the cone's revolution.
Conclusion: The correct option representing the total region covered by the shadow is \(B\).