A balloon is being inflated by pumped air at the rate of 2 cm/s. how fast is the diameter of the balloon increasing when the radius is 1/2 cm.

Question

anonymous · Answer

could u further explain the part on "A balloon is being inflated by pumped air at the rate of 2 cm/s"? I think u can use differentiation to solve it:D

minatsukisaya95 · Answer

yes it use differentiation but i quite do't understand the question 
isn't it D=2r. when differentiate it will be dD/dt= 2dr/dt
but why the question give the value of r

minatsukisaya95 · Answer

2 cm/s is dr/dt

anonymous · Answer

dD/dt=(dD/dr) x (dr/dt)
         =1 x2 =2?
kind of confused with this question im assuming dD/dr= 2 x 0.5= 1

minatsukisaya95 · Answer

i assume D=2r so the differentiate is dD/dr=2
what i don't get is how to use the r=1/2 given

anonymous · Answer

at the instance when r=1/2 the D=1cm?

minatsukisaya95 · Answer

how do we explain that?