Question

a needle of 12 cm long is on the surface of water .the extra force required over its wait to take it out from the surface of water is

Answer 1

more than the value of gravity that is more than 9.8

Answer 2

Given:

• The length of the needle = 12 cm = 0.12 m

To Find:

• The extra force required to take the needle out from the surface of the water.

Solution:

The formula to find the force due to surface tension is given by,

F = TI  → {equation 1}

Where "F" is the force due to surface tension, "T" is the surface tension of water, "l" is the length. The surface tension of water is usually 0.07275 J/$m^2$.

Substitute the values in equation 1. We get,

F = 0.0725×0.12 {multiplying the values}

F = 0.00872 N

∴ The extra force required to take the needle out from the surface of the water =  0.00872N