Question -
Answer -
Given the radius of a spherical soap bubble is increasing at the rate of 0.2 cm/sec.
To find rate of increase of its surface area, when the radius is 7 cm
Let the radius of the given spherical soap bubble be r cm at any instant time.
Then according to the given question we can write as
Rate of radius of the spherical soap bubble is increasing
Hence the rate of increase of its surface area, when the radiusis 7 cm is 11.2 π cm2/sec