From the top of a tower, a stone is thrown up and reaches the ground in time ๐ก1 = 9s. A second stone is thrown down with the same speed and reaches the ground in time ๐ก2 = 4 s. A third stone is released from rest and reaches the ground in time ๐ก3, which is equal to

Question : From the top of a tower, a stone is thrown up and reaches the ground in time ๐ก1 = 9s. A second stone is thrown down with the same speed and reaches the ground in time ๐ก2 = 4 s. A third stone is released from rest and reaches the ground in time ๐ก3, which is equal to