Q:

A garbage can is in the shape of a cylinder with no lid. It needs to have a volume of 5000 cm. What will be the radius and height of the can that uses 3 the least amount of material to construct it? *(using surface area)

Accepted Solution

A:
To minimize the material needed to construct the garbage can, we need to minimize its surface area. Since the can has no lid, its surface area is given by: A = 2πrh + 2πr^2 where r is the radius of the base of the cylinder, h is the height, and π is a constant (approximately 3.14). We are given that the volume of the can should be 5000 cm^3, so we can use the formula for the volume of a cylinder: V = πr^2h to write h in terms of r: h = V/πr^2 Substituting this expression for h into the equation for the surface area, we get: A = 2πr(V/πr^2) + 2πr^2 A = 2V/r + 2πr^2 To minimize A, we take its derivative with respect to r and set it equal to zero: dA/dr = -2V/r^2 + 4πr = 0 2V = r^3π Solving for r, we get: r = (2V/π)^(1/3) r = (2*5000/π)^(1/3) ≈ 12.3 cm Substituting this value of r into the expression for h in terms of r, we get: h = V/πr^2 h = 5000/(π*(12.3)^2) ≈ 10.2 cm Therefore, the garbage can with a volume of 5000 cm^3 that uses the least amount of material to construct it has a radius of approximately 12.3 cm and a height of approximately 10.2 cm.