Question

Until 2014, the mass of a kilogram was defined as exactly equal to the mass of a special

platinum-iridium cylinder kept in Sèvres, France. The cylinder's diameter and height are
both 39.2 millimeters.
What is the surface area of this cylinder?

Answer 1

7241.25 mm squared

Explanation:

The surface area of a cylinder is denoted by:
`A=2\pi r^2+2\pi rh`, where r is the radius and h is the height.

Here, we know that the diameter is 39.2 mm, and since diameter is twice the radius, then r = d/2 = 39.2/2 = 19.6 mm. We also know that the height is 39.2 mm, so plug these values in:

`A=2\pi r^2+2\pi rh`

`A=2\pi (19.6)^2+2\pi *19.6*39.2=7241.25` mm squared

The answer is about 7241.25 mm squared.

Answer 2

surface area: 7241.25

Explanation:

using this formula for surface area of cyclinder: 2πrh+2π
`r^2`

diameter = 2r --> 39.2 = 2r

so r= 19.6