What is the surface area of a cylindrical ring if its outside diameter is 16 mm and its inside diameter is 10 mm? Round your answer to the nearest whole number.
A. 92 mm^2
B. 118 mm^2
C. 123 mm^2
D. 385 mm^2
I thought it was C. 123 mm^2. However that is not correct, I got it wrong. Please Help.
What is the width of the cylindrical ring?
a = pi(8^2 - 5^2) = 122.52
You were correct, if they are asking about the area of the top or bottom surface of the cylinder.
However, maybe they are asking about the area of the curved surface. In that case, it would be
2pi(8-5)h
and you'd need to know the height of the ring.
The correct answer for the above problem is
D. 385 mm^2
I am 100% sure!
Was stuck on this one because the height is not provided....
To find the surface area of a cylindrical ring, you need to calculate the difference between the areas of the outer and inner circles and then multiply it by the height of the ring.
First, let's find the areas of the outer and inner circles. The formula for the area of a circle is A = πr², where A represents the area and r represents the radius.
Given that the outside diameter is 16 mm, we can find the radius of the outer circle by dividing the diameter by 2. So, the radius (r₁) of the outer circle is 16 mm / 2 = 8 mm.
Similarly, the radius (r₂) of the inner circle is 10 mm / 2 = 5 mm.
Now, let's calculate the areas of the outer (A₁) and inner (A₂) circles:
A₁ = πr₁²
A₁ = π(8 mm)²
A₁ ≈ 201.06 mm² (use π ≈ 3.14)
A₂ = πr₂²
A₂ = π(5 mm)²
A₂ ≈ 78.54 mm²
Now, you need to subtract the area of the inner circle from the area of the outer circle to get the surface area of the ring:
Surface Area = A₁ - A₂
Surface Area ≈ 201.06 mm² - 78.54 mm²
Surface Area ≈ 122.52 mm²
Since you need to round your answer to the nearest whole number, the surface area of the cylindrical ring is approximately 123 mm².
Therefore, the correct answer is C. 123 mm².