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If a solid spherical ball of iron with radius r
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08 Jun 2019, 05:16
08 Jun 2019, 05:16
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Question Stats:
20% (01:29) correct
80% (01:36) wrong based on 5 sessions
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If a solid spherical ball of iron with radius r centimetres is cut into two equal hemispheres, what is the ratio, in terms of r, of the volume and the surface area of each hemisphere?
A) 2r/9
B) r/3
C) 4r/9
D) 2r/3
E) 4r/3
A) 2r/9
B) r/3
C) 4r/9
D) 2r/3
E) 4r/3
Re: If a solid spherical ball of iron with radius r
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14 Jun 2019, 08:25
14 Jun 2019, 08:25
1
V = 4/3* Pi*r^3, for half, V(1/2)= 2/3*Pi*r^3
A= 4*Pi*r^2 , for half, A(1/2)= 2*Pi*r^2 . but in this case, you also need to consider the area of a circular region (cutting sphere in middle!). So total surface area for half of the sphere, A(1/2)= 2*Pi*r^2 =Pi*r^2 = 3 *Pi*r^2
Now, V(1/2) / A(1/2) = 2*r/9
A= 4*Pi*r^2 , for half, A(1/2)= 2*Pi*r^2 . but in this case, you also need to consider the area of a circular region (cutting sphere in middle!). So total surface area for half of the sphere, A(1/2)= 2*Pi*r^2 =Pi*r^2 = 3 *Pi*r^2
Now, V(1/2) / A(1/2) = 2*r/9
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Re: If a solid spherical ball of iron with radius r
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15 Jun 2019, 08:17
15 Jun 2019, 08:17
1
Please note that students are not required to know the formula for the volume of a sphere.
If you were given such a question on test day, the question would also include the formula for the volume of a sphere.
Cheers,
Brent
If you were given such a question on test day, the question would also include the formula for the volume of a sphere.
Cheers,
Brent
