Question 81: Properties of Matter

Question

Surface tension of a soap bubble is $$2.0 	imes 10^{-2} \mathrm{Nm}^{-1}$$. Work done to increase the radius of soap bubble from $$3.5 \mathrm{~cm}$$ to $$7 \mathrm{~cm}$$ will be:
Take $$\left[\pi=\frac{22}{7}ight]$$

Accepted Answer

Surface area of soap bubble $=2 	imes 4 \pi \mathrm{R}^{2}$ Work done $=$ change in surface energy $	imes \mathrm{T}_{\mathrm{S}}$
$=\mathrm{T}_{\mathrm{S}} 	imes 8 \pi 	imes\left(\mathrm{R}_{2}^{2}-\mathrm{R}_{1}^{2}ight)$
$=2 	imes 10^{-2} 	imes 8 	imes \frac{22}{7} 	imes 49 	imes \frac{3}{4} 	imes 10^{-4}$
$=18.48 	imes 10^{-4} \mathrm{~J}$

Answer

$$18 .48 	imes 10^{-4} \mathrm{~J}$$

Answer

$$5.76 	imes 10^{-4} \mathrm{~J}$$

Answer

$$0.72 	imes 10^{-4} \mathrm{~J}$$

Answer

$$9.24 	imes 10^{-4} \mathrm{~J}$$

Properties of Matter

Surface tension of a soap bubble is $2.0 \times 10^{-2} \mathrm{Nm}^{-1}. Work done to increase the radius of soap bubble from 3.5 \mathrm{~cm} to 7 \mathrm{~cm} will be: Take \left[\pi=\frac{22}{7}\right]

Choose the correct answer: