# Did you increase or decrease the length of the pendulum’s thread if the frequency

**Did you increase or decrease the length of the pendulum’s thread if the frequency of its oscillations was at first equal to 5 Hz, and then decreased to 3 Hz?**

Data: νн (initial oscillation frequency of the specified pendulum) = 5 Hz; νk (final vibration frequency) = 3 Hz.

The length of the thread of the specified pendulum was increased, since the frequency is inversely proportional to the length of the thread.

Proof: The change in the length of the thread of the indicated pendulum is determined using the formula: ν = 1 / 2Π * √ (g / l); g / l = ν ^ 2 * 4 * Π ^ 2 and ν ^ 2 * l = g / (4 * Π ^ 2).

The resulting equality: νn2 * ln = g / (4 * Π ^ 2) = νk ^ 2 * lk, whence we express: lk / ln = νn ^ 2 / νk ^ 2 = 5 ^ 2/3 ^ 2> 1, therefore, lk> ln, the length of the thread was increased.

Answer: The length of the thread was increased.