# Golf physics

1. Apr 13, 2003

### mchugh

hi

i'm working on a program to simulate the effects of a golf shot accurately. I allow the user to set most of the parameters - such as the mass of the clubhead, loft of the club face (angle), the radius and mass of the ball, etc.

At present, i've got a pretty lame implentation, which uses

MV(1+e)
ball velocity = -------
M+m

M is the clubhead mass, V is the velocity of the club (which I rotate to be perpendicular to the club face) e is the restitution of the ball and m is the mass of the ball.

For the project to be a success, it needs to take into account spin imparted to the ball. For this to happen, as i understand, i need to calculate a normal and tangental force. I can calculate the direction vectors of these forces no problem, but does anyone know more about how this stuff works? Once i have these two forces, I then have to work out spin (as angular velocity ideally), which in turn i need to use to calculate magnus force, so i can get a proper flight on the ball.

All the parameters are set specifically for the point of impact - that is to say, i only give the clubhead a speed, which is the presumed speed at the point of impact. I appreciate that this can be a problem, as I might need to use the acceleration of the clubhead to work out some force stuff. If this is the case, then i will need a 'fix' to provide a suitable figure for the acceleration.

you might be able to see the program as it is (depending on wether or not the free web host i use is working) at http://mchugh.port5.com/images/golf.jpg, [Broken] an image which demonstrates the inaccuracy of the ball flight at the minute (golf balls dont fly like that).

feel free to talk to me like a baby. any help or pointers to resources on the matter would be greatly appreciated.

thanks

Last edited by a moderator: May 1, 2017
2. Apr 15, 2003

### Staff: Mentor

Its actually pretty complicated. The velocity of the club is parallel to the ground, not perpendicular to the face. Like light in a reflection problem, a 10.5 degree driver actually produces a 21 degree (with respect to the club head, not the ground) loft. More later...gotta gl.

Last edited by a moderator: May 1, 2017