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Grade 12Mechanics

A hollowcone and a hollow hemisphere having same base .hight of cone is H,and radius of hemisphere is R. What is max ratio of H/R so.it will stable when is displaced. It come its originals position. ....pls ans using com

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8 Years agoGrade 12
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1 Answer

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ApprovedApproved Tutor Answer1 Year ago

To determine the maximum ratio of the height of a hollow cone (H) to the radius of a hollow hemisphere (R) for stability when displaced, we need to analyze the conditions under which these shapes can return to their original positions after being disturbed. Stability in this context is often assessed using the concept of the center of mass and the base of support.

Understanding the Shapes

First, let’s visualize the two shapes:

  • The hollow cone has a circular base with radius R and height H.
  • The hollow hemisphere also has the same base radius R.

Both shapes share the same base, which is crucial for our analysis of stability.

Center of Mass Considerations

The center of mass (CM) is the point where the mass of a body is concentrated. For stability, the center of mass must remain above the base of support when the object is displaced. If the CM moves outside the base, the object will topple.

Finding the Center of Mass

For the hollow cone, the center of mass is located along the axis of symmetry at a height of:

CM_cone = H/3

This is because the center of mass of a cone is located one-third of the way from the base to the apex.

For the hollow hemisphere, the center of mass is located at:

CM_hemisphere = 3R/8

This is derived from the geometry of the hemisphere, where the center of mass is positioned along the vertical axis.

Stability Condition

To ensure stability, we need the center of mass of the cone to remain above the base when the object is tilted. This means that the height of the center of mass of the cone must not exceed the radius of the hemisphere when displaced. Mathematically, this can be expressed as:

H/3 ≤ R

Deriving the Ratio

From the inequality above, we can rearrange it to find the maximum ratio of H to R:

H ≤ 3R

Thus, the maximum ratio of height to radius is:

H/R ≤ 3

Conclusion on Stability

In summary, for the hollow cone to remain stable when displaced, the maximum ratio of its height (H) to the radius of the hollow hemisphere (R) must be 3. This means that if the height of the cone exceeds three times the radius of the hemisphere, it will not return to its original position after being disturbed. Understanding these geometric relationships is essential in fields such as engineering and architecture, where stability is a critical factor in design.