ROCK MECHANICS Basics Rock mechanics concerns itself with how rocks will react when one rock strikes another at different angles. Scenario: Blue shooter rock is being delivered approximately parallel to the centerline and will strike the first of two object rocks at 1/2 rock position which means the outer edge of each rock will impact at 45degrees as indicated by the first black arrow. The first rock would strike out at very closely the angle of impact if it were sitting alone. The second or more of a series of "touching" rocks will also kickout at the same angle (little bit less). This reaction is accomplished by the friction between the striking surfaces. Since the friction is not 100%, with each object rock added, the angle of deflection will decrease. So, the second object rock in the picture will deflect at a slightly smaller angle. And with any spaces up to 3-4", the angle of deflection will decrease to a point where the angle will be reversed and the last even numbered rock will deflect in the opposite direction from the number one object rock. HOW to Remember? Envision all intermediate rocks removed and your shooter is striking the last in the "chain" of object rocks. The more rocks, the lower will be the angle of deflection. Spaces up to 2" changes (reduces) the deflection angle radically. |
 Remember: Hit first (remove 1 rock ) -- Roll Second and remove #2 for a "double" hit AND "stick." The across the face hit and direct hit allows the shooter a margin of deflection error. The target zone is 33", the width of 3 rocks. Of course, you lose energy on a subsequent hit if the deflected shooter hits a small portion of another object rock. Curling is a game of mathematics, percentages and millimeters. Give yourself every strategy advantage possible by evaluating your shooter's and brusher's skills and the condition of the ice. Remember too, what you, the skip, can or can not make.  Recap: The across the face hit produces a lower angle of refraction/deflection due to the reversal of rock spin and friction loss between hitting surfaces. The energy in the shooter is LESS and will skid less. With the reversal of rotation, at low exit speeds, the shooter will curl to recover part of the lost angle. The object rock has more resultant energy after the hit than the shooter and rebounds at 90degrees minus 60degrees=30degrees. Basically, a direct inturn hit at 1/2 rock will produce a deflection of 30-31 degrees for the shooter and 59-60 degrees approx. for the object rock for a total of 90degrees when added together. The energy is shared proportional to the angle of deflection if each deflects unequally. Energy is directly proportional to the angle of refraction. The resultant energy of a rock deflected at 60 degrees (object rock) is higher than a rock deflected at 30 degrees (the shooter rock). All energy from the shooter rock is transmitted to a nose hit (90 degrees) object rock. In summary: Sometimes, it is desirable to hit an object rock such that you want the shooter to rebound at a lower angle with less energy i.e., you want the shooter rock to hang around in the house. HIT ACROSS the face!  |