Question

A ring is cut from a platinum tube 8.5 cm internal and 8.7 cm external diameter. It is supported horizontally from the pan of a balance, so that it comes in contact with the water in a glass vessel. If an extra 3.97. If is required to pull it away from water, the surface tension of water is(a) 72 dyne cm⁻¹(b) 70.80 dyne cm⁻¹(c) 63.35 dyne cm⁻¹(d) 60 dyne cm⁻¹

Answer 1

Answer:(a). The surface tension of water is 72 dyne/cm

Explanation:

Given that,

Internal diameter = 8.5 cm

External diameter = 8.7 cm

Extra mass = 3.97 gram

We know that,

Force due to surface tension along the internal and external circumference of platinum tube = weight

$T\pi(Internal\ diameter + External\ diameter) = mg$

$T\pi (8.5 cm +8.7 cm) = 3.97\ gram\times980 cm/s^{2}$

$T = \dfrac{3.97\times980}{3.14\times 17.2}$

$T = 72\ dyne/cm$

Hence, the surface tension of water is 72 dyne/cm

Answer 2

Answer:

i think the above one is right