Question

Water rises in a capillary tube to a height $ h $ . Choose false statement regarding capillary rise from the following:

• A. On the surface of Jupiter, height will be less than h
• B. In a lift moving up with constant acceleration height is less than h
• C. On the surface of moon the height is more than h
• D. In a lift moving down with constant acceleration height is less than h
• E. At the poles, height is less than that at equator

Answer 1

Answer: (D)

The height (h) to which water rises in a capillary tube is given by
$ h=\frac{2T\cos \theta }{r\rho g} $ where $ \theta $ is angle of contact, r the radius, $ \rho $ the density and g acceleration due to gravity. When lift moves down with constant acceleration, height is less than h, because effective value of acceleration due to gravity increases hence h decreases.