The length of a needle floating on the surfac | vedclass

Name: Exam Paper Generator | JEE NEET Paper Generator | Vedclass
Brand: Vedclass
Rating: 5 (35 reviews)

Question

(A) When a needle is floating on the surface of water,the surface tension acts along the length of the needle on both sides.The total length of contac

Vedclass · Accepted Answer

$22.5$

Vedclass · Answer

(A) When a needle is floating on the surface of water,the surface tension acts along the length of the needle on both sides.The total length of contact is $L_{total} = 2 	imes L = 2 	imes 1.5\,cm = 3.0\,cm$.The force required to lift the needle,in addition to its weight,is given by the formula $F = T 	imes L_{total}$,where $T$ is the surface tension.Given $T = 7.5\,N/cm$ and $L_{total} = 3.0\,cm$.$F = 7.5\,N/cm 	imes 3.0\,cm = 22.5\,N$.

The length of a needle floating on the surface of water is $1.5\,cm$. The force in addition to its weight required to lift the needle from the water surface will be...... $N$ (surface tension of water $= 7.5\,N/cm$).

Similar Questions

$A$ thin metal disc of radius $r$ floats on the water surface and bends the surface downwards along the perimeter,making an angle $\theta$ with the vertical edge of the disc. If the disc displaces a weight of water $W$ and the surface tension of water is $T$,then the weight of the metal disc is:

Why do colours and lubricating oil have less surface tension?

In the case of the surface of one fluid in contact with another fluid or a solid surface,what does the surface tension/surface energy depend on? Explain with an illustration.

Soap helps in cleaning clothes,because

It is better to wash clothes in hot water than in cold water. Explain.

Vedclass Test Series

Exam Paper Generator

Online Exam Module