Jun 25, 2010

Do you know why golf balls have dimples?

An educational carnival of fun and discovery at the science in the mall.

It's a great fun activity for kids during the school holiday. There are few activities for the kids to have a hand on experience. My girl likes to experience on every activity, the one she likes more is the mini golfing or what they call mini putting green.

Do you know why the golf balls have dimples? This question never ever cross my mind until I read the little note book provided at the carnival.

It said, when air flows around a round ball, it tends to flow more smoothly around the first half of the ball, but creates instability as it continues its flows behind the ball. This instability show the ball down and shortens its flight.

When the surface of the ball is dimpled, air flowing around the ball becomes more stable. The dimples allow the air to flow smoother, so there is less drag and the ball flies farther.

The dimples also effect the golf ball's spin. With the golf club's angled shape, a hit will cause the ball to backspin, and lifts it up. The dimples further lift the ball up, due to the air caught on top of the ball. That explains why golf balls have dimples.

There are other activities such as checking out your BMI, do you know how to count your body mass index? it's your weight (kg) divide by height x height.

It a risk of developing heart disease and diabetes if your BMI is 23 and above.
Knowing your BMI will give you an early warning to take action to lower your weight to reduce your risk and to seek medical advice if your BMI exceeds 23. (Source from hpb)
There is also a test of how high can you jump, how springy are you, what's your grip, how's your balance and how fast are you. All can be tested using tools provided at the carnival. (for more info science)

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