2 8 8 π . The chocolate is then melted down and reshaped into a solid cube. Assume no chocolate was wasted.
A solid sphere of chocolate has a volume ofDid the sphere have a greater surface area or does the cube?
Useful equations:
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Firstly, we are given that the Sphere is melted down and reshaped into a Cube, with no waste. Therefore their volumes must be the same. So we have (using the equations given in the question): 3 4 π r 3 = 2 8 8 π a 3 = 2 8 8 π Therefore we can say that the radius of the sphere and the side-length of the cube is: r = 6 a = 9 . 6 7 Therefore, using the formulas given, we can calculate the surface areas to be: A s p h e r e = 4 π r 2 = 4 ⋅ 3 . 1 4 ⋅ 6 2 = 4 5 2 c m 3 A c u b e = 6 a 2 = 6 ⋅ 9 . 6 7 2 = 5 6 1 c m 3 Therefore the cube has a greater surface area than the sphere, so the correct answer to the question is: T h e C u b e
Obviously, the cube has more surface area as spheres have the least amount of surface area to pack a certain volume, as we see in soap bubbles. (We can't have a bubble with a shape other than sphere)
Excellent solution! I love the elegance of it - relating it to packing problems!
volume of sphere = 288π
4/3 * π * r^3 = 288π
r = 6 units
surface area of a sphere = 4 * π * r^2 = 4 * π * 6^2 = 452.39 square units
volume of cube = volume of sphere = 288π
s^3 = 288π
s = 9.67 units
surface area of cube = 6 * s^2 = 6 * 9.67^2 = 561.05 square units
surface area of cube > surface area of sphere
Mathematically, the cube has a higher surface area by the equations in other answers. However, the problem is flawed. There had to have been chocolate that accidentally didn't make it into the cube - it's a law of cooking with chocolate, some ends up in your stomach.
volume of sphere = 288π
4/3 * π * r^3 = 288π
r = 6 units
surface area of a sphere = 4 * π * r^2 = 4 * π * 6^2 = 452.39 square units
volume of cube = volume of sphere = 288π
s^3 = 288π
s = 9.67 units
surface area of cube = 6 * s^2 = 6 * 9.67^2 = 561.05 square units
surface area of cube > surface area of sphere
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Consider the sphere: Compute r from V . We have
2 8 8 π = 3 4 π ( r 3 ) ⟹ r = 6
So the surface area of the sphere is S s p h e r e = 4 π r 2 = 4 ( π ) ( 6 2 ) ≈ 4 5 2 . 3 9
Consider the cube: Compute a from V , we have
2 8 8 π = a 3 ⟹ a ≈ 9 . 6 7
The surface area of the cube S c u b e = 6 ( 9 . 6 7 2 ) ≈ 5 6 1 . 0 5
∴ The cube has a larger surface area.