A capillary tube 20 cm long is dipped in water, causing the water to rise up to 8 cm . If the complete arrangement is placed inside a freely falling elevator, determine the length of the water column in the capillary tube.

Step-by-step solution

The height of capillary rise is given by the formula: h = 2T r g_ eff In a freely falling elevator, the effective acceleration due to gravity is zero ( g_ eff = 0 ). As g_ eff 0 , the theoretical height h . However, the liquid cannot overflow from the upper end of the capillary tube. Instead, the liquid rises to the top of the tube and the meniscus adjusts its radius of curvature R such that h R = constant . Thus, the water will rise to the full length of the capillary tube. Since the total length of the capillary