1. The Physics of Golf
By Drew Thomassin
Drew Thomasson

2. Types of Clubs
Driver/Woods-Longest club, used for long distances, either: wood, titanium or stainless steel
Irons- Range from a 2 iron, less angled for farther distance to greater angled wedge for short distance
Putter- Used for puts on the green

3. Parts of the Club
Head- Woods-wood, titanium, stainless steel Irons- stainless steel, titanium, iron
Shaft- steel, carbon fiber, resin composite
Grip- rubber or leather

4. Contact with the Ball
The contact between the club head and the ball is less than a thousandth of a second.
The average force between the ball and the club head is around 3000 lbs, the ball becomes flattened against the clubface
The ball when hit it rolls up the clubface due to friction and flies off with a high speed above the horizontal (where the clubface made contact with the ball)
The momentum of the collision is conserved because of the high speed of the ball after the collision and the slowing down of the club head during the collision
The collision is not elastic meaning that mechanical energy was lost during the collision when the ball flattened and rolls up clubface due to friction
The clubface has grooves on it, to produce friction for the ball to roll up clubface and to produce a spin on the ball

5. The D Plane
This is a representation of perfect contact between the clubface and the ball
The path which the club is moving at impact
The normal to the clubface and the path after the collision
As well as the aerodynamic lift force

6. A Hook Shot
A hook shot is when a right handed golfer makes first contact with the side of the ball furthest away from him
A clean hit will cause the ball to spin at a horizontal axis
Contact like this results in a spinning axis to the left causing the ball to curve to the left
The whole D plane is shifted to the left

7. A Slice Shot
A slice shot happens when a right handed golfer makes first contact with the ball on the inner side
Like in a hook shot this contact results in the ball to spin towards the right making it curve to the right

8. History of the Golf Ball
The “feathery” was the first golf ball. It was a leather spherical pouch filled tightly with feathers and then stitched. When the ball hardened it became very hard, then was oiled and painted.
These golf balls would reach up to150 to 175 yards
Featheries were used until 1848 when the gutta-percha was invented.
The gutta-percha is a gum from trees in Malaysia.
Became roughened, people realized they’d go much further than smooth balls
Modern golf ball range in they’re made of these days, the typical golf ball has a core made of polybutadiene, a type of rubber
Harder core, farther they go
Golf balls today can reach up to 300 +

9. Flight of the Ball

10. Diagram A Streamline flow – still, straight airflow
Turbulent flow- disturbed air flow
Slow streamline air flow past smooth ball
At a low velocity there is a thin layer of air near the surface of the ball called the boundary layer, where the speed of air is zero, as it extends out the air speed becomes greater in the streamline flow
Air in contact with the ball is at rest relative to the surface of the ball
Momentum is transferred across the boundary layer from the flowing air to the surface of the ball
From A to B the boundary layer is going from high pressure to low pressure, the pressure difference helps increase velocity
Direction of Ball

11. Diagram B
Air flow at a higher speed past a smooth ball, showing turbulence
From A to B streamline is similar to diagram A
At B the turbulent wake forms
Energy is lost, from the energy of motion (Kinetic Energy),
A drag is created from the difference of pressures between the front and back of the ball
Direction of Ball
Velocity of air past a well hit golf ball is much greater, a streamline wont occur

12. Diagram C Turbulent flow past a dimpled ball, no spin
The dimple surface makes the boundary layer turbulent
Instead of air slowing near B, the fast moving air carries the turbulent boundary along with the ball, to extend further along the surface of the ball from the lower air pressure level at B to the higher air pressure level at C
Drag of the dimpled ball is smaller than the smooth ball, less energy is dissipated in the smaller wake
Direction of Ball

13. Diagram D
Air flow downstream from a rotating dimpled ball, golf ball flight
When hit, the ball slides up the face of the club due to the friction of the ridges
The ridges cause the ball to spin on a horizontal axis spinning towards the golfer
The turbulent layer is moving with the surface of the ball as it spins
Air at top is moving more rapidly than air at the bottom, the pressure is less above the ball than below the ball
A lift force is exerted perpendicularly on the ball
The wake behind the ball starts lower than the wake of the non-spinning ball
Ball receives a downward momentum, the ball recoils in upward motion
Direction off Ball

14. Drag and Lift
Depend on three variables: speed of ball through the air, the rate of spin on the ball, surface texture of the ball
Drag on the ball increases with speed through the air and spinning rate
Lift increases with rate of spin at a given air speed and vise versa
Different clubs vary in loft resulting in a more intensive spin or less intensive spin
Clubs also vary in the power to be given to the ball
Depends a lot on the club for the amount of drag and lift

15. References entertainment.howstuffworks.com/golf-club.html
Jorgensen, Theodore P., The Physics of Golf, American Institute of Physics Press, Woodbury, NY. 1994
sportsillustrated.cnn.com/augusta/cool_stuff/physics/tiger.html