Wednesday, February 25, 2015

The Ball that Defied Gravity ... or Did it? (Science Experiment)

Even very young kids understand gravity. So when a science experiment seems to defy it, they're mega impressed.

This fun activity wowed my boys. Okay, okay, okay … it kinda wowed me too.

What You Need
Ping-pong ball
2 unsharpened pencils
deck of cards
small book

What to DoKids should separate the deck of cards into two equal piles. Put the piles side-by-side so they're touching.

Take the pencils (eraser end)  and place them on the card piles. The tips of the erasers should almost be touching and as they angle down to the table top, should open up to an inch or slightly larger. Note: We used round pencils. I'd recommend you use traditional pencils (is that a hexagon?).

Ask your child to predict what will happen when the ball is placed at the top (eraser side) of the pencils. They'll tell you the ball will roll down the pencils. They're right.

Now separate the decks of cards and flip the pencils around, so the eraser tips are resting on the table and they open up so the unsharpened ends are resting on the card decks.

Place a small book over the eraser ends to weight them down and hold them in place.
Ask your child what will happen when you place the ball about an inch above the erasers. Will it roll back down and hit the book? They'll say yes, because gravity pulls things down, right?

Now put the ball in place and be astonished. The ball appears to roll up the pencil ramp, defying gravity.

How it Works
While it seems as if the ball defies gravity, truthfully, it doesn't. As the pencils spread apart, the ball slips between them, being pulled by the force of gravity toward the table. It just so happens that the pencils are angled up and so that's the direction the ball rolls as it drops down.

This great activity came from a truly phenomenal book. Smart Science Tricks is packed with simple experiments that seem like magic and use materials you most likely have around your house already. Check it out!

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