The trombone's low B flat 2 is played with the slide in first position. What is its effective length, that is the length of an idealized closed tube with the same second mode frequency? Estimate how far the slide should be moved to reach second position in order to play A2, remembering that each cm of slide motion adds 2cm to the tube length. If already in sixth position(F2), how much farther must you move the slide to reach seventh position (E2)?