Sphere

1. Describe the properties of the sphere and its parts:

  • sphere
  • spherical layer (shell)
  • spherical segment
  • spherical sector
  • spherical cap / zone

Solution:

Sphere

r – radius
d – diameter

gula-1

Spherical layer

p1, p2 – radii of the cross-sections
v – height of the layer

gulova-vrstva

Spherical segment

r – radius of the sphere
p – radius of the segment
v – height of the segment

gulovy-odsek

Spherical sector

r – radius of the sphere
v – height of the segment

gulovy-vysek

Spherical cap or zone

r = radius of the sphere
v = height of the cap or zone

S = 2π.r.v

2. The table lists values characterizing spheres.

Complete the table.

gula-2
Solution:

gula-2r

3. Three spheres with radii r1 = 3 cm, r2 = 4 cm, r3 = 5 cm are to be melted and cast into one sphere.

What will be the radius of this sphere?
Solution:

gula-3

The radius of the new sphere will be R = 6 cm.

4. A cube is inscribed in a sphere with radius r = 6 cm.

What percent of the sphere’s volume does the cube’s volume constitute?
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5. What is the mass of a hollow brass sphere (ρ = 8.5 g·cm-3) if the outer diameter is D = 12 cm and the wall thickness is h = 2 mm?

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6. A sphere and a cone are inscribed in a right circular cylinder.

Determine the ratio Vk : Vg : Vv.
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7. A planar cross-section of a sphere has length l = 125.6 cm. The distance of the section from the center of the sphere is v = 6 cm.

Determine the sphere’s radius and its volume.
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8. A spherical segment with height v = 5 cm has volume V = 850 cm3.

Determine the radius r of the original sphere.
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9. The height of a spherical cap equals one third of the sphere’s radius.

In what ratio is the sphere’s surface area to the area of the cap?
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10. Calculate the mass of a biconvex glass lens (ρ = 3.5 g·cm-3) with diameter 10 cm and thickness 1.2 cm.

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