Question

A spool of thread has an average radius of 1.00 cm. If the spool contains 62.8 m of thread, how many turns of thread are on the spool? "Average radius" allows us to not need to treat the layering of threads on lower layers.

Answer 1

To solve this problem we will start from the given concept in which the number of turns is equivalent to the length of the thread per circumference of spool. That is:

$N = \frac{l}{\phi}$

Where,

l = length of the thread

$\phi$= circumference of spool

For \phi we have that,

$\phi = 2\pi r \rightarrow 2\pi (0.01)$

For l  we have that

l = 62.8m

Finally the number of Turns would be,

$N = \frac{l}{\phi}$

$N = \frac{62.8}{2\pi (0.01)}$

$N = 1000turns$

Therefore the number of turns of thread on the spool are 1000turns.