This pipe under my kitchen sink has a big crack in the area circled in yellow. (It's on the back side so it isn't visible in the photo.) Can I simply unscrew the nut at the top that I circled in red to replace the pipe? I'm afraid to just go ahead and try in the fear that I will put my kitchen sink out of commission. I'm already ok with disconnecting the hand-tightened nut at the bottom.
Success! I replaced the tailpiece with no problem. Thanks to all for the help.