Center of mass / momentum chain

[mattyisphtty]

Homework Statement

Given: A uniform flexible chain whose mass
is 4.1 kg and length is 5 m. A table whose top
is frictionless.
Initially you are holding the chain at rest
and one-half of the length of the chain is hung
over the edge of the table. When you let loose
of the chain it falls downward.
The acceleration of gravity is 9.8 m/s2
Find the acceleration a of the chain when
the length of the chain hanging vertically is
3.6 m: Answer in units of m/s2.

Homework Equations

The Attempt at a Solution

Well I am not exactly sure to figure this out, but it seems as if it would be extremely easy to do seeing as how the acceleration due to gravity is 9.8. unfortunately this is wrong but I have yet to figure out what other force would be giving it an acceleration other than 9.8

 

[mattyisphtty]

Any help would be much appreciated.

 

[mattyisphtty]

Alrighty well thank you very much for helping. The second part of the question is asking for the velocity at that point. Rather than an answer could anyone help me with what to start with for this point seeing as how the acceleration is varying. Thanks.

 

[blochwave]

Sorry, I think I was wrong. I'm not entirely sure why the acceleration isn't just g. If nothing else it should be constant

 

[mattyisphtty]

Actually you were right lol. I calculated the hanging mass when there is that much of the chain hanging. I got 2.9252kg the divided that by the entire mass and came out with the correct answer for the acceleration. Now all I need is how to find the velocity at that point.

 

[Shooting Star]

Same problem. Just a few days back. Check this thread:

https://www.physicsforums.com/showthread.php?t=202557