A soap film of surface tension 3 times 10^{-2 | vedclass

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(B) The soap film has two surfaces,so the total upward force due to surface tension is $F = 2Tl$,where $T$ is the surface tension and $l$ is the lengt

Vedclass · Accepted Answer

$0.6$

Vedclass · Answer

(B) The soap film has two surfaces,so the total upward force due to surface tension is $F = 2Tl$,where $T$ is the surface tension and $l$ is the length of the straw.For the straw to be supported,the weight of the straw must be balanced by this force: $mg = 2Tl$.Given: $T = 3 	imes 10^{-2} \, N/m$,$l = 10 \, cm = 0.1 \, m$,and taking $g \approx 10 \, m/s^2$ for simplicity in calculation.$m = \frac{2Tl}{g} = \frac{2 	imes (3 	imes 10^{-2}) 	imes 0.1}{10} = \frac{0.6 	imes 10^{-2}}{10} = 0.6 	imes 10^{-3} \, kg$.Converting to grams: $m = 0.6 	imes 10^{-3} 	imes 10^3 \, g = 0.6 \, g$.

$A$ soap film of surface tension $3 \times 10^{-2} \, N/m$ is formed in a rectangular frame and can support a straw. The length of the film is $10 \, cm$. The mass of the straw the film can support is ........ $g$.

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