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Example: A mercury barometer shows a mercury column height of 760 mm at sea level. If the atmospheric pressure drops and the column height decreases to 700 mm, what is the new atmospheric pressure in pascals? Step 1: Know the density of mercury (ρ) = 13,600 kg/m³. Step 2: Convert the heights to meters: 760 mm = 0.760 m, 700 mm = 0.700 m. Step 3: Use the formula P = ρ g h, where g = 9.81 m/s². Step 4: Calculate the initial pressure: P₁ = 13,600 × 9.81 × 0.760 ≈ 101,300 Pa. Step 5: Calculate the new pressure: P₂ = 13,600 × 9.81 × 0.700 ≈ 93,500 Pa. Step 6: The pressure has decreased by about 7,800 Pa. Answer: The new atmospheric pressure is approximately 93,500 pascals.