==================================================== Newsletter - Issue 140 Date 06/20/10 ==================================================== ==================================================== TCT Quick Tips - Fall Line ==================================================== When you approach the green, you must try to find the fall line around the hole. Imagine a bucket of water being poured around the hole. The fall line would be the direction in which it flows. There will be no break up or down the fall line and maximum break across it. Remember that uphill breaking putts will break considerably less than similar downhill breaking putts. Enjoy, Tom ==================================================== Golf Tip: Impact and Sweet Spot ==================================================== What happens at Impact? 1) In the first microsecond of impact, we have the irresistible force meeting the immovable object. The ball has to react somehow to the momentum of the clubhead, and the least-energy way it can react is by moving up the lofted clubface. Initially it slides up the clubface, because there isn't enough friction yet between clubface and ball. But all that is about to change very quickly. 2. The ball cannot accelerate to an upwards velocity in no time at all; that would require infinite acceleration, which requires infinite force. So it can't get completely out of the way of the clubhead just by sliding upwards. It begins to compress on the clubface, which creates a force between the clubface and the ball. If you don't think this is a large force, just try to compress a golf ball by 30% of its diameter using your fingers. Not even close! OK, use a vise; it's still very hard to apply that much compression force. Remember, this is a force that averages almost 2000 pounds during impact, and can easily peak around 3000 pounds. This force of compression does two important things: a) It begins to accelerate the ball with a horizontal component, not just the vertical motion up the clubface. b) It creates a lot of friction between ball and clubface. So, instead of sliding up the clubface, the ball begins to roll instead. 3. The ball continues accelerating upwards (due to the loft) and horizontally (due to the compressive force). The sliding has turned completely into roll, so the upwards acceleration increases the speed of roll. At some point, the momentum absorbed from the clubhead through acceleration has the ball moving faster than the clubhead. In other words, the elastic rebound of the ball's acceleration allows the ball to release from the clubhead. At this instant, its launch conditions are determined. The Sweet Spot All clubs have the same size sweet spot. The sweet spot is equivalent to the club head’s center of gravity. This spot is about the size of the tip end of a needle. Also, the club only has one sweet spot in spite of one company’s advertising that their driver has 9 different sweet spots. If you hit the ball squarely and in the center, the ball will fly straight and true and as far as your club head speed will allow. Enjoy, Tom