Thread: Problem from D. Morin's "Introduction to Classical Mechanics"

I'm getting incorrect results solving Problem 3.30 Atwood's 4 from 3.7 Exercises of Morin's book, 2008 edition.
According to my solution, the lowest mass in the Fig.3.23 of the book for N=3 has an acceleration greater than g - acceleration of gravity, which is not possible for the problem's conditions. It looks like my 'conservation of string' equation - acceleration of the lowest mass is 4 times greater than acceleration of the top mass - is wrong.
Any help?

Originally Posted by gainwmn

I'm getting incorrect results solving Problem 3.30 Atwood's 4 from 3.7 Exercises of Morin's book, 2008 edition.
According to my solution, the lowest mass in the Fig.3.23 of the book for N=3 has an acceleration greater than g - acceleration of gravity, which is not possible for the problem's conditions. It looks like my 'conservation of string' equation - acceleration of the lowest mass is 4 times greater than acceleration of the top mass - is wrong.
Any help?

Can you please give the problem statement and show what you tried? Only after that we can try helping.

Thanks, I have already figured it out on my own.

Originally Posted by gainwmn

Thanks, I have already figured it out on my own.

Very happy to hear that -- congratulations!

If you have a similar request in future, I would suggest including the actual problem statement, rather than a reference to a textbook. Otherwise, you're limiting your pool of potential respondents to those who happen to have a copy of that book (and that particular edition of that book). Help us help you.

The actual problem statement wouldn't work anyway, since it is very difficult to describe in words the pic. of the Atwood machine in question that is given in the book, and I could not draw it using the very limited capabilities of your site, otherwise I would have certainly done that.

Originally Posted by gainwmn

The actual problem statement wouldn't work anyway, since it is very difficult to describe in words the pic. of the Atwood machine in question that is given in the book, and I could not draw it using the very limited capabilities of your site, otherwise I would have certainly done that.

Understood -- the limitations of the site do intrude at times. As a workaround, you can upload diagrams and text to something like Dropbox, and post a link to that material here.