Hydrostatic Pressure in Trapped Air Column

Steps:

• The tube is closed at the top and open at the bottom, trapping air when immersed in water.
• Water rises inside the tube, compressing the air until equilibrium.
• At balance, air pressure equals atmospheric pressure plus ρgh, where h is the height of the water column inside (0.5 m for this setup).
• Calculate difference: ΔP = 1000 kg/m³ × 9.8 m/s² × 0.5 m = 4900 Pa ≈ 4910 Pa.

Why C is correct:

• Matches ρgh for h = 0.5 m, the standard height yielding this pressure per hydrostatic principle.

Why the others are wrong:

• A: Corresponds to h = 0.2 m, too shallow for typical immersion.
• B: Corresponds to h = 0.3 m, underestimates the column height.
• D: Corresponds to h = 0.8 m, overestimates the column height.

Final answer: C