# The Naked Scientists Forum

### Author Topic: How does mud affect the dimples on a golf ball?  (Read 3446 times)

#### raghusesha

• Jr. Member
• Posts: 14
##### How does mud affect the dimples on a golf ball?
« on: 17/06/2010 17:30:02 »

Hi,

I am from Bengaluru, India and I am a great newbielink:http://www.thenakedscientists.com/HTML/podcasts/ [nonactive].  I find your newbielink:http://www.thenakedscientists.com/HTML/podcasts/ [nonactive] exteremely interesting.

In your show on 14 feb 2010, you answered a question on the aerodynamics in a golf ball.  The summary of the discussion was that if we have a smooth surface, the air flow from both the sides is exactly same and hence there is no force acting in either direction and hence the object (golf ball) goes straight.  But if there is some mud, the ball will go on the opposite side of the mud.

When I apply the same logic to an airplane wing, I get confused.  The upper surface of the wing has extra bulge (equivalent to mud) and the lower surface is flat.  The wing gets a force to move upwards (in the direction of the extra bulge) due to low pressure created by higher velocity.  Now, this is in contradiction to what was explained for the golf ball.

My guess was that it could be due to the fact that the extra bulge on wing is smooth while the mud on ball is rough.

Later, I saw an article where I saw that the dimples on the golf ball are added so that the air sticks on for longer time.  If that is the case (making the surface not so smooth causes air to stick on for longer distance), then why does mud not make it to stick on for much longer?

Regards,
Raghu S

What do you think?
« Last Edit: 17/06/2010 17:30:02 by _system »

#### graham.d

• Neilep Level Member
• Posts: 2208
##### Re: How does mud affect the dimples on a golf ball?
« Reply #1 on: 18/06/2010 09:40:22 »
I suggest washing your balls regularly :-)

#### krytie75

• Full Member
• Posts: 57
##### Re: How does mud affect the dimples on a golf ball?
« Reply #2 on: 18/06/2010 16:05:57 »
@graham.d - Lol! Best post of the century....

#### raghusesha

• Jr. Member
• Posts: 14
##### How does mud affect the dimples on a golf ball?
« Reply #3 on: 21/06/2010 08:03:45 »
I was hoping to get a better answer.

#### graham.d

• Neilep Level Member
• Posts: 2208
##### How does mud affect the dimples on a golf ball?
« Reply #4 on: 21/06/2010 09:18:35 »
I'm sorry raghusesha, I couldn't resist a joke. I would hope that someone with more specific knowledge than I have would answer you but I will have a more serious attempt.

The dimples on the golf ball will cause more turbulence. The turbulence reduces the drag on the ball in a similar way to a spoiler on a fast car; it reduces the size of the low pressure region behind the ball during flight. Additionally, it enhances the effect of any spin by translating the angular momentum of the spin into a curve in the trajectory. This is similar to how a footballer curves a shot at goal but, for the most part, not the way a swing bowler in cricket causes a cricket ball to curve. The golf ball always tends to get backspin so this, and the spoiler effect, will lengthen the flight. A side effect is that slicing and hooking is also more prominent.

I am not so sure of the effect of mud because it would have different effects depending on how much was there. If it just evenly filled in the dimples I would assume it would largely negate the effects of them. If it filled the dimples on one side the effect would be erratic because it would be unlikely that the ball would not rotate and it would not be possible to predict where the mud filled side would be at any point in its flight. This is in contast to the cricket ball where the flight time is short and the seam acts as a rudder to maintain the polished side and the rough side as the bowler desires (if he is a good bowler). A lump of mud on one side (if it stayed there) is even more complex to analyse and beyond my ability to judge. It would depend on many factors such as the size, shape, weight and texture.

I hope this is a better answer.

#### raghusesha

• Jr. Member
• Posts: 14
##### How does mud affect the dimples on a golf ball?
« Reply #5 on: 24/06/2010 05:00:40 »
Thanks Graham.d, I was thinking if the bulge on the wings of place will have the same effect as mud on the ball.  From your post, it looks like they are completely different and we cannot apply the same principles.

#### The Naked Scientists Forum

##### How does mud affect the dimples on a golf ball?
« Reply #5 on: 24/06/2010 05:00:40 »