Have you ever wondered why golf balls have dimples or why your hair goes frizzy in the rain? Scientist Wendy Sadler has the answers in her book of Weird and Wonderful facts. Broken down into user-friendly chapters like sport, going out, the great outdoors, food and drink and the downright weird, Wendy gives the scientific answers to life's intriguing questions, like
- Why toast always lands butter side down
- Why you can't get (too) lost with a satnav.
Why do golf balls have dimples?
In the beginning, golf balls were smooth. But then golfers began to notice that the older and rougher the balls got, the further they would fly. The old scuffed-up balls were in big demand, though no-one really understood what was going on.
Common sense would suggest that smooth things should cut through the air more easily. Cars and boats that are designed to go as fast as possible usually have smooth surfaces and streamlined shapes. The force that slows things down in air is called drag, so how come a rough ball would give you less drag?
When a smooth ball travels through the air, the air flowing around it doesn’t meet up nicely at the back of the ball. The path of air over the top and the path underneath split up and create an area of turbulence behind the ball that slows it down. But if you take a ball with a rough surface, the air flowing around it sticks to the ball longer until the air almost meets up again neatly at the back. The fact that the air doesn’t split so early on means there is much less drag at the back of the ball. This in turn means it isn’t held back and flies much further.
The shape, pattern and depth of the dimples can make a difference, too. Most golf balls have round dimples, but some now use hexagon shapes which make the drag even less. The dimples are usually arranged in a pattern that is the same all over the ball but in the 1970s one company made golf balls with a special design where the dimples were deeper in some parts of the ball than in others. This helped the ball correct itself in flight. These were banned from use in competitions but can still be bought for private use if you need a bit of help on the golf course! If you ever find yourself with too much time on your hands you could try counting the dimples in your golf ball to see where it was made. American ones have 336 and British ones have 330!
Wendy Sadler is the founding Director of science made simple - the award-winning company which specialises in making science inspirational and fun. She has written 19 books for children, presented three series of What On Earth? for ITV Wales and is a contributor on BBC Radio Wales. Her simple science theatre show has toured 19 countries and appeared at the Edinburgh Festival Fringe. Wendy is currently employed by Cardiff University.