A clock with a metal pendulum beating seconds keeps correct time at 0°C. If it loses 12.5 s a day at 25°C, the coefficient of linear expansion of metal pendulum is

Number of seconds lost in a day,  Δt=12αΔθ×86400The coefficient of linear expansion of metal pendulum,                        α=2ΔtΔθ×86400=2×12.525×86400⇒               α=186400/C  ∘