## Question

A ring is cut from a platinum tube of 8.5 cm internal and 8.7 cm external diameter. It is supported horizontally from a pan of a balance so that it comes in contact with the water in a glass vessel. What is the surface tension of water is an extra 3.97 g weight is required to pull it away from water? (*g* = 980 cm/s^{2})

### Solution

72.13 dyne/cm

The ring is in contact with water along its inner and outer circumference; so when pulled out the total force on it due to surface tension will be

= 72.13 dyne/cm.

#### SIMILAR QUESTIONS

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