Search: To find out answers to a specific question, copy a representative sentence from the question and paste the sentence in the search form and search it. The results show the most related questions and yours may be in there. Feel free to share LeiAcademy.org with other teachers and students.  
To discourage spam, only registered users can ask questions.

Welcome to Physics Homework and Study Help, where you can ask questions and receive help on learning physics. We currently focus on helping questions in introductory level college physics and high school AP Physics courses.
To discourage spam, only registered users can ask questions.

Facebook Twitter Google

Welcome to Physics Homework Help Page on LeiAcademy.org

Feel free to ask a question and also answer questions others asked. Answering others' questions can in turn help one's own understanding and build a warm healthy community for learning. The followings list a few things that might be helpful for you to effectively obtain help on specific physics homework or practice problems.  

Search: To find out answers to a specific questions, copy a representative sentence from the question and paste the whole sentence in the search form and search it. The results will show the most related questions and yours may be in there

Browse: To find out what have been discussed, asked or answered, put in a few key words in the search form and search for related questions, answers, and or solutions. Or you can click the related tags or other tabs to find useful information there. 

You can also write professional-looking equations using Latex codes (see details here).

This site is hosted on LeiAcademy.org, which will continue to add new resources for learning. Feel free to share this with other teachers and students.  

A 2 ft diameter trommel screen is used to separate municipal refuse.

0 votes
2,018 views

A 2 ft diameter trommel screen is used to separate municipal refuse. Estimate its critical speed.

asked Mar 4, 2014 in Others by tracig2401 (240 points)

1 Answer

0 votes
The critical speed (\( N_c \) of a trommel screen is the speed necessary to hold the materials contained against the wall throughout a complete revolution and is given in rotations per sec. The only forces acting on particles along the wall are the normal force and gravity which should cause circular motion. The minimum rotational velocity of the trommel will result in no normal force at the top of the rotation of the trommel.

$$ F = m r \omega^2= mg $$

$$\omega = 2 \pi N_c$$

So our critical speed is:

$$ N_c = \sqrt{ \frac{ g}{4 \pi^2 r}} $$

Keep in mind that g and r need to be in similar units (feet per sec^2 and feet).
answered Mar 10, 2014 by jcf1559 (2,140 points)
web counter
...