The Force of Gravity

We are continuing our Cosmic Education with lots of Earth Science studies. The First Great Lesson lead us into the study of Astronomy and Physical Sciences. We've talked about the planets, the sun, the moon, stars and other celestial bodies.

I picked up this fun book from the library and we read it today. It is called Why doesn't the Earth fall up? And other not such dumb questions about motion. by Vicki Cobb. T is 7 years old so the title of this book interested him. If you put the word "dumb" in it he finds it hilarious. We did not read the entire book but excerpts in the area of gravity. It is a cute book and I recommend it if you can find it at your library.

Why doesn't the Earth fall up?

We also borrowed the book Gravity is a Mystery by Franklyn Mansfield Branley. This book is from the '80s so the drawings are very retro. It was a cute book and my son was thrilled because it compares all of the weights in the book to 60lbs which is about his weight. It gives a comparison of what your weight is on other planets and the sun if you weigh 60lbs. If your child is another weight you could calculate the weights but I was happy I didn't have to go that far. A child who was a bit more advanced at math could use that as a project to figure out themselves.

Gravity is a Mystery

T is all about experiments and I had already told him that I had an experiment waiting for him. He was very excited to receive his first experiment card to do the experiment on his own. The experiment cards are simply blank index cards with experiments printed on them and the explanation printed on the back.
The materials and procedure are listed step by step for him to follow. He collected his materials and headed out to our backyard.

This particular experiment I first read about in a book called Montessori Today by Paula Polk Lillard. In the Appendix there is a section called "A Student's Reflections" where a former student recounts the first time she did this experiment in her Montessori school. It is also described in great detail in our Montessori R&D Functional Geography manual. Basically, you tie a rope (or a dog leash in our case) to the handle of a small bucket. The bucket is them filled about 3/4 full of water. The child swings the bucket over their head in large circles and then observes what happens.

Yes, that is a McDonald's happy meal halloween bucket we are using. And we used a dog leash instead of a rope because that is what I had on hand.

The water stays in the bucket

Centrifugal Force pulls the water outward keeping it in the bucket

He was worried he might get soaked at first

Centripetal Force keeps the bucket moving in a circular path

When the Centripetal Force (his arm) was removed from the rope the bucket flies off in a straight line (this part we did with an empty bucket)

T LOVED this experiment! He was outside doing this experiment for about an hour. He spent most of that time doing the empty bucket part when he let go of the bucket trying to see if go off in a straight line. Then he came inside and we reviewed the terms Centrifugal Force and Centripetal Force using some simple cards I made.

If you have an energetic early elementary child I highly recommend this experiment. We all know that the more interested they are the more the lesson sticks. I think my son will remember these forces for a long time. Maybe one day he will think back on this lesson the way the former student did in Montessori Today.