Spring Period — Oscillating Scale Pan (Worked Example)

Problem

A 2.0 kg mass hangs from a spring of constant 250 N/m and is set oscillating vertically. What is the period?

Given

  • m = 2.0 kg

  • k = 250 N/m

Find

The period T.

Principle

Vertical or horizontal, a mass-spring system obeys T = 2π√(m/k) for small oscillations.

Formula

Solution

  1. Write the formula: T=2πm/kT = 2\pi\sqrt{m/k}

  2. Substitute: T=2π2.0/250T = 2\pi\sqrt{2.0/250}

  3. Inside: 2/250=0.0082/250 = 0.008; 0.008=0.0894\sqrt{0.008} = 0.0894

  4. Multiply: T=2π×0.0894=0.562 sT = 2\pi \times 0.0894 = 0.562\ \mathrm{s}

0.562 s

Unit check

√(kg ÷ kg/s²) = s — correct.

What this means physically

0.562 s — about 1.78 oscillations per second. Heavier masses swing slower; this square-root dependence is why adding mass is an easy way to slow a vibration down.

Common mistake

Including g in the formula. Gravity stretches the spring's rest position but does not change the oscillation period.