Machine-translated by Google. Questions are authored in English.
Top

Discussion

A spring of spring constant k is cut into n pieces of equal length. The force constant of any one of the pieces is

  • A.\(\frac{n^{2}}{k}\)
  • B.\(\frac{k}{n}\)
  • C.\(nk^{2}\)
  • D.\(\frac{n}{k}\)
  • E.\(nk\)

Answer: E

The force constant of each piece is \(nk\).

For a spring of given material and coil, the spring constant is inversely proportional to its length: \(k \propto \frac{1}{L}\). Each piece is \(\frac{L}{n}\) long, so its constant is \(n\) times larger.

A check: the n pieces joined end to end in series must give back the original spring, and \(n\) springs of constant \(nk\) in series give \(\frac{nk}{n} = k\).

\(\frac{k}{n}\) has the proportion the wrong way round; a shorter spring is stiffer, not softer. \(nk^{2}\), \(\frac{n^{2}}{k}\) and \(\frac{n}{k}\) do not even have the units of a spring constant.

No comment is present. Be the first to comment.
Loading…

Post your comment

Please log in or register to post a comment.