Generally Eclectic

Physics and the Swing's Movements

Chapter Eleven: Guide to the Golf Swing

It's elementary (my dear Watson)

THE PHYSICS OF COCKING AND UNCOCKING THE WRISTS.

Cocking and uncocking the wrists was discussed in Chapter 2. The picture below summarizes the key physical aspects of the movement.

Wrist Rotation

THE PHYSICS OF THE FOREARM ROLL

The forearm roll is discussed in Chapter 3. The picture below summarizes the key aspects of the forearm roll:

Forearm Rotation

THE PHYSICS OF ROTATING THE UPPER ARM IN THE SHOULDER SOCKET

The rotation of the upper arm in the shoulder socket was addressed in Chapter 5. The physics of upper arm rotation in the shoulder socket are the same as the forearm roll, with the same rotation centre, axis of rotation, and distance to the ball.

THE PHYSICS OF MOVING THE UPPER ARMS IN THE SHOULDER SOCKET

Chapter 4 discussed the proper movement of the upper arm in the shoulder socket. The picture below illustrates key physical components of the movement:

Upper Arm Rotation

THE PHYSICS OF MOVING THE SHOULDER SOCKETS

Shoulder socket rotation was addressed in Chapter 6, which noted that the forward movement of one shoulder socket and the backward movement of the other socket, in combination, lead to a rotation of the shoulder sockets around the spinal column.

The picture below illustrates the key aspects of this movement:

Spine Rotation

THE PHYSICS OF THE SPINAL TWIST

The spinal twist was discussed in Chapter 7. The physics of the spinal twist are almost identical to that of moving the shoulder sockets.

THE PHYSICS OF HIPS ROTATION AND SPINAL TILT

As noted above, there are four ways in which hip rotation can be executed:

Pure Rotation without Spinal Tilt

The picture below illustrates key aspects of the physics of Pure Rotation, without tilting the spine.

<span class=Pure Rotation Without Tilt" class="width60">

Push and Clear without Spinal Tilt

There are three aspects of Push and Clear without spinal tilt.

Pure Rotation with Spinal Tilt

The spinal tilt involves lateral side bending. The amount of lateral side bending is generally that amount required to keep the head/eyes/shoulder centre stable in the face of movement away from this stable centre that would come from hip rotation and the forward lean. The physics of Pure Rotation with spinal tilt involves (1) calculating the effect on club speed from hip rotation when the "forward lean" effect is neutralized by spinal tilting, (2) calculating the amount of lateral movement being neutralized by the spinal tilt, and (3) determining the effect on club speed from the spinal tilt, given the amount of lateral movement neutralized by the spinal tilt.

In the discussion of Pure Rotation without spinal tilt, the forward lean widens the circle that the club head would follow as a result of the hip rotation. The picture below illustrates the physics of Pure Rotation with spinal tilt.

Hips With Spinal Tilt

To calculate the club head speed from hip rotation:

As discussed above, the rotation combined with forward tilt in the absence of spinal tilt causes lateral movement of the shoulder sockets. The diagram looks at the golf swing from the top and illustrates this lateral movement. The red dotted circle is the path that the mid-point in the shoulder socket would trace as a result of hip rotation with forward lean. The diagram shows that there will be lateral movement away from the target in the back swing.

Spinal Tilt Rotation

Calculating the amount of lateral movement comes through a two step process.

The first step involves calculating the radius of the rotation circle for the mid-point between the shoulder sockets. We can calculate the distance from the hip joints to the mid-point between the shoulder sockets through measurement. We can determine the angle between the vertical and the forward leaning spine through a picture and protractor. The radius of the rotation circle is the sine of the spine angle times the distance between the mid-point between the hip joints and the mid-point between the shoulder sockets.

The second step involves the calculation of the lateral movement. From the first step, we can calculate the radius of the rotation circle. We can know the amount of hip rotation by observing individual golf swings. The amount of lateral movement is the sine of the angle representing the hip rotation times the radius of the rotation circle.

The picture below illustrates the physics of the spinal tilt. In essence, the spinal tilt involves two rotation circles with a common centre. One circle is the tilting shoulders circle, while the other is the club head circle.

The amount of rotation in the tilting shoulders circle is also the amount of rotation in the club head circle.

Regarding the tilting shoulders circle:

Regarding the club head circle:

Forearm Rotation

Push and Clear with Spinal tilt

The physics of the Push and Clear with spinal tilt has four elements:

The basic rotation effect is based on the same physics as described under Pure Rotation with spinal tilt, except that the amount of rotation will be less because Pure Rotation has two hips moving while the Push and Clear keeps the trailing hip in a fixed place and includes movement only in the lead hip.

The physics of calculating the amount of rotation resulting from hip rotation in conjunction the forward lean are outlined in the section on Pure Rotation with spinal tilt, except the amount of rotation will be less because there is less rotation in Push and Clear.

There is a certain amount of lateral movement intrinsic to the Push and Clear, and this amount is independent of the forward lean.

Assuming the spinal tilt functions to a large extent to keep the head still in the back swing and downswing while lateral movement is occurring, the amount of spinal tilt in the Push and Clear with spinal tilt will be the sum of the lateral movement from the basic rotation and the lateral movement intrinsic to the Push and Clear movement.

The physics of calculating the impact of the spinal tilt on club head speed resulting from a given amount of lateral movement will be the same as that described in the section on Pure Rotation with spinal tilt.

The Bottom Line