The length of a needle floating on water is 2.5 cm. Calculate the added force (due to surface tension) required to pull the needle out of water. (Surface tension of water =7.2× 10-2N/m2 )

Question

The length of a needle floating on water is 2.5 cm. Calculate the added force (due to surface tension) required to pull the needle out of water. (Surface tension of water =7.2× 10-2N/m2 ) (A)  3.6× 10-3N  (B)  3.4× 10-10N  (C)  3.0× 10-5N  (D)  3.8× 10-11N

Tardigrade Admin · Accepted Answer

The force of surface tension F=T-2l =7.2× 10-2× 2× 2.5× 10-2 =3.6× 10-3N

Q. The length of a needle floating on water is 2.5 cm. Calculate the added force (due to surface tension) required to pull the needle out of water. (Surface tension of water $= 7.2 \times 10^{- 2} N / m^{2}$ )

$3.6 \times 10^{- 3} N$

$3.4 \times 10^{- 10} N$

$3.0 \times 10^{- 5} N$

$3.8 \times 10^{- 11} N$

The force of surface tension $F = T - 2 l$ $= 7.2 \times 10^{- 2} \times 2 \times 2.5 \times 10^{- 2}$ $= 3.6 \times 10^{- 3} N$

Q. The length of a needle floating on water is 2.5 cm. Calculate the added force (due to surface tension) required to pull the needle out of water. (Surface tension of water =7.2×10−2N/m2 )

3.6×10−3N

3.4×10−10N

3.0×10−5N

3.8×10−11N