Golf Ball Physics

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Title: How do the dimples on a golf ball affect its flight? When a golf ball is hit, there are many forces acting on it which affect its trajectory. The lift forces are greater than the weight and the drag force, which act in the opposite direction of the ball’s path and downwards. [2] All objects which fly through the air are under interaction with forces of lift and drag. When a golf ball is struck it has lots of backspin, changing the flow of air around the ball, produces lift which is the force that acts perpendicular to its flight path. This is due to a difference in pressure, the pressure the bottom of the ball is much higher than the pressure at the top of the ball. [2] Another force experienced by the golf ball is drag, a force acting…show more content…
Given that there is no friction, the air flowing around the sphere forms a perfectly symmetrical pattern. Now we need to consider the pressure distribution of the surface of the sphere. The difference between high-pressure regions and low-pressure regions create the aerodynamic forces on the sphere, for example lift and drag, and leads to the Magnus effect which is where the pressure decreases where the speed of the fluid increases. The pressure at the front of a sphere is very high, so the air impacting on the front face creates drag. The pressure at the back of a sphere is very high as well, this creates a thrust (negative drag) which effectively works to cancel out the drag on the front of the sphere. So, theoretically this tells use there should be no drag on a sphere. However, experimental data shows that a sphere definitely does generate drag. [4] The reason why the theory contradicts with the experimental data is that the theory ignores friction. The actual flow around a sphere is very different to the theory as friction causes flow separation. Flow separation means the flow isn’t symmetrical. The actual flow does not follow the surface of the entire rear face of the ball. The flow no longer remains attached to the ball. The point at which the flow separates from the surface is called the separation point. The separated flow is dominated by unsteady vortices that create a wake. [4]

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