THE FOLLOW THROUGH PHASE
Once the ball is in flight, there are,
again, a number of factors that may affect its displacement.
If the ball is hit on either side of
the sweet spot on the club face, it creates sideways spin on the ball, and will
cause the ball to either hook or slice (curve sideways during flight).
Similarly, if the ball is hit from too low on the club face (hitting the top of
the ball), it will create topspin, and the Magnus effect will cause the ball to
drop sooner than it should (YOU TUBE REF). If the ball is hit from underneath
with the top of the club face, it will create too much vertical velocity and
not enough horizontal, and therefore will not be projected as far as it
possibly could.
The Magnus Effect (or Magnus Force) occurs
when there are different air speeds on either side of the spinning ball
(Blazevich, 2008, p. 178), making the air change the direction in which it is
travelling. For example, if the air on the right-hand side of the ball is
travelling in the same direction as the spin of the ball, that air is dragged
along the surface of the ball, and travels faster than the air on the left side
of the ball, which is travelling in the opposite direction to the ball’s spin,
meaning that the air will slow right down, creating air pockets and high
relative pressure on that side, that will lift or direct the ball in the
direction of the spin (Blazevich, 2008, p. 178; Veritasium, 2011)
See video below for further explanation.
Picture: Magnus Force around a golf ball.
Video: Detailed explanation of the Magnus Force. (Source: Veritasium, 2011, November 24)
When analyzing how to play a shot, one must think about the effect of drag on propulsion. How much wind is there, and how strong is it? Is it blowing from behind, or is it a headwind? Is it warm, or is there rain, sleet or hail? If there is lightening, be sure to not play at all, but the other environmental constraints play a large part in the flight of the ball. Drag is essentially air forces that resist motion, and therefore affect the propulsion rate of the ball (Blazevich, 2008, p. 152). Lloyd (1990) reported that heated golf balls travel further than unheated ones, as the friction around the ball is reduced when the ball is in flight, and therefore the ball would lower the air resistance around it.
The dimples in a golf ball are an
important asset to it that many people are not aware of. They trap air
particles in and around them whilst the ball is in flight, creating a boundary
layer, and an accumulation of air molecules at the front of the ball, so that other
molecules are separated from the laminar flow earlier, and can flow more effortlessly
around the ball (Blazevich, 2008, p. 138); a smooth ball would have a much
bigger accumulation of air molecules around its surface, and therefore would
not travel as far (See pic below).
