# Measuring Moment Of Inertia For A Water Bottle During A Flip

1 reply to this topic

### #1 cardistryMagic

cardistryMagic

Curious

• Members
• 1 posts

Posted 30 January 2018 - 10:11 AM

Hey,

For a physics project, my partner and I are trying to measure the moment of inertia vs. time for a water bottle during a water bottle flip. Our setup is as follows:

-          Green screen

-          Water bottle throwing apparatus

-          Two lights illuminating the water bottle and green screen

-          Water bottle full of red dye

Our method is the following:

1.       Film the bottle flip in slow motion

2.       Extract all the frames

3.       Use a program I wrote to analyse the amount of red in the pixels in different parts of the water bottle as more light will pass through less dense areas (areas where there is less dye, hence less water). We would do summation for all the pixels and their estimated point masses for moment of inertia

The program works fine, but the problem we’ve encountered so far is the reflection of light from the bottle itself (see the attached photo). This messes up the program as some parts of the bottle just reflect back white light.

If anyone has any ideas on how to solve this problem, or a whole new method of measuring moment of inertia for a water bottle during a flip, please comment! We’re open to any ideas.

Edit: The photo I attached is shown with the bottle completely full, but in the experiment it would only be filled about 30-50%.

Thanks

#### Attached Files

Edited by cardistryMagic, 30 January 2018 - 10:12 AM.

### #2 exchemist

exchemist

Creating

• Members
• 2841 posts

Posted 31 January 2018 - 02:45 AM

Hey,

For a physics project, my partner and I are trying to measure the moment of inertia vs. time for a water bottle during a water bottle flip. Our setup is as follows:

-          Green screen

-          Water bottle throwing apparatus

-          Two lights illuminating the water bottle and green screen

-          Water bottle full of red dye

Our method is the following:

1.       Film the bottle flip in slow motion

2.       Extract all the frames

3.       Use a program I wrote to analyse the amount of red in the pixels in different parts of the water bottle as more light will pass through less dense areas (areas where there is less dye, hence less water). We would do summation for all the pixels and their estimated point masses for moment of inertia

The program works fine, but the problem we’ve encountered so far is the reflection of light from the bottle itself (see the attached photo). This messes up the program as some parts of the bottle just reflect back white light.

If anyone has any ideas on how to solve this problem, or a whole new method of measuring moment of inertia for a water bottle during a flip, please comment! We’re open to any ideas.

Edit: The photo I attached is shown with the bottle completely full, but in the experiment it would only be filled about 30-50%.

Thanks

I'd have thought this would be virtually insoluble. The moment of inertia of the bottle will change during the process if it is part-filled, due to motion of the water. I wish you luck.