# Describe the physics of a golf ball flight off the club face

• papagrande
In summary: So, the ball has to undergo an extra, rotational motion, in order to hit the ground at the same time as it hits the club face. This additional motion is called "spin" and it's due to the fact that the ball is spinning while it's in the air. Baseball fielders and pool players understand this extra spin and take advantage of it by hitting the ball high in the air with side spin.
papagrande
How did you find PF?: social media

The flight of a golf ball off the club face at the moment of strike would seem to be determined, among other variables such as elasticity, by the mass of the ball, the club's force vector, and the orientation of the club face relative to that force vector. In first approximation, it seems the ball would reflected off the club face at an angle twice that of the angle between the club face and the force vector. To visualize this, rather than swinging the club, imagine throwing the ball at a surface such as club face fixed in space, and observing that the ball would reflect off of the surface at an angle mirroring the angle of incidence.

Conservation of energy, though, must account for spin. When the ball hits the surface (or the club face hits the ball) it spins more or less depending on the angle of incidence. Either the angle of reflection or the speed of the ball, or both, must be affected somehow by the energy consumed inducing spin on the ball. Baseball fielders report a base hit, with the ball bouncing rapidly towards them hops higher or lower depending on its spin, with the back spinning ball hopping higher than the top spinning ball. Pool players similarly employ side spin on their shots to affect the angle of reflection on bank shots, the cue ball spinning clockwise towards the bank reflects at an angle further clockwise than the one spinning the other way.

In this thought experiment, the limiting case seems to be the club with a 45 degree loft. If the shot direction is defined by simple reflection, the 45 degree loft would send the ball straight up, which is not experienced in a normal shot.

Any thoughts on how to calculate the direction and spin of a golf ball at launch off the club face at the moment of strike?

Delta2
Hi papagrande

This is the New Member Introductions area. For your questions please use the appropriate forum. Is this a homework question?

Moved to classical physics.

papagrande said:
How did you find PF?: social media

The flight of a golf ball off the club face at the moment of strike would seem to be determined, among other variables such as elasticity, by the mass of the ball, the club's force vector, and the orientation of the club face relative to that force vector. In first approximation, it seems the ball would reflected off the club face at an angle twice that of the angle between the club face and the force vector. To visualize this, rather than swinging the club, imagine throwing the ball at a surface such as club face fixed in space, and observing that the ball would reflect off of the surface at an angle mirroring the angle of incidence.

Conservation of energy, though, must account for spin. When the ball hits the surface (or the club face hits the ball) it spins more or less depending on the angle of incidence. Either the angle of reflection or the speed of the ball, or both, must be affected somehow by the energy consumed inducing spin on the ball. Baseball fielders report a base hit, with the ball bouncing rapidly towards them hops higher or lower depending on its spin, with the back spinning ball hopping higher than the top spinning ball. Pool players similarly employ side spin on their shots to affect the angle of reflection on bank shots, the cue ball spinning clockwise towards the bank reflects at an angle further clockwise than the one spinning the other way.

In this thought experiment, the limiting case seems to be the club with a 45 degree loft. If the shot direction is defined by simple reflection, the 45 degree loft would send the ball straight up, which is not experienced in a normal shot.

Any thoughts on how to calculate the direction and spin of a golf ball at launch off the club face at the moment of strike?

For your more general question you would be better to look online for some material on the theory of golf club design.

If you analyse a club with a 45 degree loft hitting a ball using the rest frame of the club, then the ball will go approximately vertically up in that frame. But, it doesn't go vertically up in the rest frame of the tee.

## 1. What factors influence the trajectory of a golf ball off the club face?

The trajectory of a golf ball off the club face is influenced by several factors, including the angle of the club face at impact, the speed of the club head, the spin of the ball, and the air resistance or drag on the ball.

## 2. How does the angle of the club face affect the flight of a golf ball?

The angle of the club face at impact determines the initial direction of the ball. If the club face is open, the ball will tend to go to the right, while a closed club face will cause the ball to go to the left. The angle of the club face also affects the amount of backspin on the ball, which can impact its distance and trajectory.

## 3. What role does the speed of the club head play in the flight of a golf ball?

The speed of the club head is a major factor in determining the distance a golf ball will travel. The faster the club head, the more energy is transferred to the ball, resulting in a longer flight. However, too much speed can also cause the ball to spin more, which can affect its trajectory.

## 4. How does spin on a golf ball affect its flight?

Spin on a golf ball can greatly impact its flight. A ball with backspin will tend to fly higher and have more carry, while a ball with topspin will have a lower trajectory and more roll. Side spin can also cause the ball to curve in one direction or the other.

## 5. How does air resistance or drag affect the flight of a golf ball?

Air resistance, or drag, can greatly affect the flight of a golf ball. As the ball moves through the air, it experiences drag that can slow it down and change its trajectory. This is why golf balls with dimples, which reduce drag, can travel farther than smooth balls.

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