Question

The radius of a circular pipe is 10 cm. What length of tape is required to wrap once around the pipe? (Take $\pi =3.14$)

Answer 1

Hint: We have to wrap the tape around the pipe once. So, we can just consider the pipe to be a circle with a radius of 10 cm. This means that the length of the tape required will be the same as the circumference of this circle. We will use the formula for the circumference of the circle, which is given as $C=2\pi r$ where $r$ is the radius of the circle.

Complete step by step answer:
We have a circular pipe that has a radius of 10 cm. We have to wrap tape once around this circular pipe. So, the length of the tape required will be equal to the circumference of the pipe. The pipe is circular, so the circumference of this pipe is the same as the circumference of a circle with the same radius as that of the pipe.

The formula for the circumference of a circle is given as $C=2\pi r$ where $r$ is the radius of the circle. We have $r=10$ and $\pi =3.14$. Substituting these values in the formula for circumference of circle, we get the following,
$\begin{align}
  & C=2\times 3.14\times 10 \\
 & \therefore C=62.8\text{ cm} \\
\end{align}$
Hence, the length of tape required to wrap around the pipe once is 62.8 cm.

Note:
It is important that we understand the geometric shapes and objects. We should be familiar with the formulae for calculating the circumference, area, volume, etc for standard geometric objects. Most of the time, when we see the word 'pipe', we assume it to be a cylinder. So, there is a possibility of confusion in this question. But it is very clearly mentioned that the pipe is circular. So, we should use the formula for the circumference of a circle and we should not concern ourselves with the cylinder any more.