### Author Topic: Puzzling rolling bottle/jar  (Read 17392 times)

#### tanghb

• Newbie
• Posts: 12
##### Puzzling rolling bottle/jar
« on: November 05, 2011, 02:32:44 pm »
Why does a cylindrical bottle/jar keep rolling back and forth once given an initial push, like a SHM? It is really a SHM? If so, what force becomes the restoring force (F=-kx) ? Please watch this video: http://youtu.be/nosZ2p07YJo

The motion of the jar in the video is not very smooth, probably due to its irregular surface. If the jar or bottle is perfectly cylindrical, and the floor is also perfectly horizontal, the motion should be smooth. Similar motion is observed when the jar/bottle is partially/fully filled with water.

Could someone explain such a motion?

#### ijfdyht89

• Newbie
• Posts: -2
##### Re: Puzzling rolling bottle/jar
« Reply #1 on: June 20, 2012, 04:57:33 pm »
I just want to change the freefall animation to be a non-parabolic horizontal animation.
You can see the particle goes frome north to south. I only want it to go from left to right like this

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#### jonihalish

• Newbie
• Posts: 1
##### Re: Puzzling rolling bottle/jar
« Reply #2 on: April 07, 2013, 04:47:02 pm »
very nice site looking so good loving article i like this blog.
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#### Fu-Kwun Hwang

• Hero Member
• Posts: 3062
##### Re: Puzzling rolling bottle/jar
« Reply #3 on: April 09, 2013, 09:18:49 am »
Why does a cylindrical bottle/jar keep rolling back and forth once given an initial push, like a SHM? It is really a SHM? If so, what force becomes the restoring force (F=-kx) ? Please watch this video: http://youtu.be/nosZ2p07YJo

The motion of the jar in the video is not very smooth, probably due to its irregular surface. If the jar or bottle is perfectly cylindrical, and the floor is also perfectly horizontal, the motion should be smooth. Similar motion is observed when the jar/bottle is partially/fully filled with water.

Could someone explain such a motion?
I hope the following simulation might help to solve it.

Full screen applet or Problem viewing java?Add http://www.phy.ntnu.edu.tw/ to exception site list
• Please feel free to post your ideas about how to use the simulation for better teaching and learning.
• Post questions to be asked to help students to think, to explore.
• Upload worksheets as attached files to share with more users.
Let's work together. We can help more users understand physics conceptually and enjoy the fun of learning physics!

#### lookang

• Hero Member
• Posts: 1772
• http://weelookang.blogspot.com
##### Re: Puzzling rolling bottle/jar
« Reply #4 on: December 31, 2018, 10:17:19 am »