Sunday, April 3, 2011

Mad Scientist Monday

Centripetal Force

What is Centripetal Force? 

It is the force necessary to make an object move in a circle.  It is directed perpendicular to the velocity of the object, which means it points toward the center of the circle. (Exploring Creation with Physical Science, p. 261) 

Here are three general principles regarding centripetal force:

1) Circular motion requires centripetal force,

2) The larger the centripetal force, the faster an object travels in a circle of a given size.

3) At a given speed, the larger the centripetal force, the smaller the circle.

Items needed:

1 plastic bucket
2 cups water
sturdy sting, if necessary


First, see if the bucket can be easily held at knee height of the person doing the experiment.  If not, add a sturdy string to the bucket handle to achieve the proper placement.

Next, place about 2 cups of water into the bucket.  Do not add too much water, or the bucket will be too heavy for the experiment. 

Now, quickly move the bucket in a circular motion like a ferris wheel.

Thought Questions:

What happens to the water?  What happens if your change the speed of your circular motion?  What happens if you change the size of the circular motions, moving the bucket in a smaller or a larger circle?  What did you observe about centripetal force from this experiment?

Two of my teens are completing Apologia's Exploring Creation with Physical Science.  I replaced this experiment with the Chapter 11.1 experiment.  This was a lot more fun!



  1. This is a great experiment, as long as there is not a crowd gathered around, and the handle on the bucket breaks.

  2. Tony... the bucket was basically new until ... afterwards my son tossed the bucket in the air to watch the water fall! Broken bucket!

  3. I will be back to see more of your Mad Scientist Mondays! What a great feature!

    Stopping by from the HHH. Hope you have a wonderful week!

  4. oh that looks like a really fun experiment! Stopping by from HHH!

  5. Love your site. I'm doing lots of science at my site and am looking for more middle school activities so I make link up to you in the future.
    new follower from the HOp and I followed you on Twitter

  6. Science experiments are one of my favorite things about homeschool.


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