Where Is Your Center of Gravity?

Dollar bill. One foot. One wall. Where Is Your Center of Gravity?

Foot

Did you ever challenge your friends to do things you didn’t think they could do?

This came from Strainertin.com, a site with a number of tricks to play with your friends.

You challenge them to do something that seems perfectly simple.

Then, you set it up and they find out they can’t do it after all.

The Setup

Challenge your grandchildren to let you put a dollar bill on the top of their foot. Tell them that, no matter how flexible they are, they will not be able to bend over and pick it up off the top of their foot.

They won’t believe you and will start demonstrating right away that, of course, they can bend down and touch their foot.

The Challenge

You ask them to stand with their backs and their heels against a wall.

You put a dollar bill on the top of their foot.

Challenge them to lean over and pick up the dollar bill.

They will not be able to do it.

What Is Happening?

In order for you to lean over and touch your feet, you have to change your center of gravity.

That means that while your top half is leaning down, your middle has to shift weight to balance you. There is no room to do this with your back to the wall.

You lose your balance when you try.

You have just taught your grandchildren something about the center of gravity and a fun trick to play with their friends.

Where Else Does the Center of Gravity Matter?

You balance over your center of gravity when you learn to ride a bike.

You attach a tail to a kite to stabilize it. The center of gravity is the point where you can balance the kite on one finger.

The tail helps keep the kite from rotating around the center of gravity in the wind. Click here to play with a NASA kite modeling program.

Knowing the center of gravity is important in ship hull design to keep it from capsizing.

It’s important when flying a plane. Airlines determine how best to load luggage in the cargo hold to account for the center of gravity of the plane and increase maneuverability.

It’s important for rocket ships, to aid in calculating their trajectory.

It is important to keep the center of gravity low when loading fire trucks, so they will be more stable.

Everyday Life

Can your grandchildren think of any other ways the center of gravity is useful?

Can they hop on one foot?

What happens when they swing? How do they keep swinging?

Why do skiers huddle over their knees?

To you and the fun and exciting world you explore with your grandchildren.

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Carol Covin, “Granny-Guru”

Author, “Who Gets to Name Grandma? The Wisdom of Mothers and Grandmothers”

http://newgrandmas.com