The Key to a good, solid golf swing is relaxation.
Many golfers have difficulty reducing the tension in hands and body.
One result of this tension is arms that are tight. In an effort to straighten it, the arm becomes rigid. It is nearly impossible to make a swing when your arms are tight and rigid. At address you want to bend forward from your hips, knees slightly flexed and let your arms hang straight down from your shoulders. Bring your hands together in front of you, still allowing them to hang naturally.