The frequency of fundamental note of an open organ pipe double than for closed pipe of same length. Why ?

Ans: We know that the fundamental frequency of an open organ pipe is given by:

fo=v2l

 Where v is the velocity of sound in air and l is the length of organ pipe.
Also, the fundamental frequency of a closed organ pipe is given by:

fo=v4l

So, the frequency of fundamental note of or an open organ pipe double than for closed pipe of same length.