Question

Determine the energy stored in the surface of soap bubble of radius 2.1 cm if the tension is

Answer 1

Energy stored in soap bubble = work done to form the bubble.

= 2 x S x A

where S - surface tension of the soap surface

and A - Area of the surface

A = 4π (radius)^2

you know the radius i.e. 2.1 cm = 0.021 m

you must have the value of S.. or any other parameters to find S..

Hope .. it helped ...

Answer 2

Explanation:

Radius= 2.1×10^-2 .

Surface tension,T = 4.5 × 10^-2.

No. Of free surfaces in a soap bubble = 2 ( explained in pic).

Area of sphere = 4 pi r^2

Surface energy = T × area × no. of free surfaces.

(4.5 ×10^-2) × [ 4×3.14×(2.1×10^-2)^2] × 2

= 498.50 ×10^-6.

= 4.98 ×10^-4. J