Question

Two pendulums of lengths 1.69 m & 1.44 m start swinging together. After how many vibration will they swing together?

• A. 8
• B. 10
• C. 12
• D. 14

Answer 1

We know

nT₁ = (n + 1) T₂ = t

so T₁ = 2p$\sqrt{\frac{1.69}{g}}$ = 1.3 × 2p$\sqrt{\frac{1}{g}}$

T₂ = 2p$\sqrt{\frac{1.44}{g}}$ = 1.2 × 2p$\sqrt{\frac{1}{g}}$

so n × 1.3 × 2p$\sqrt{\frac{1}{g}}$ = (n + 1) × 1.2 × 2p$\sqrt{\frac{1}{g}}$

Ž n = 12