# Mechanical Engineering HW help.

• Apr 12th 2011, 12:38 PM
Alpina540
Mechanical Engineering Math help.
I am confused about how to work this problem can anyone take a crack at it? My work is shown in a post below.

Thanks for any and all help!

If the spring is released from rest in the position shown in the picture , the spring contracts pulling the mass to the right. Find the Velocity of the mass when the string and the spring are parallel.

Mass = 1 kg

Spring Constant = K= 800 N/m

Unstretched length of Spring= 1m

Find same answer by using both methods

A) Principle of work and energy
B) Conservation of Energy
• Apr 12th 2011, 01:55 PM
pickslides
Please refer to rules #6, #8 and #11 in the following link

http://www.mathhelpforum.com/math-he...hp?do=vsarules
• Apr 12th 2011, 02:32 PM
Alpina540
I am asking for help, on a math problem in a math help forum... Rule #6 doesn't apply.

I am asking the same question just solved two ways. Rule #8 doesn't apply

I wasn't aware I needed to include my work toward a solution to get help. I will post it now.

A)

Work from point 1 to 2 = 1/2 kx1 -1/2 kx2

81.0=9.81(-.235) v^2

.235 = distance between mass at Position 1 vs position 2

B)
T1 + V1=T2+V2
0+1/2(2000)(.081^2)=1/2(1/9.81)V^2 + (1) .235

V=11.141m/s
• Apr 12th 2011, 06:40 PM
Ackbeet
Quote:

Originally Posted by Alpina540
I am asking for help, on a math problem in a math help forum... Rule #6 doesn't apply.

pickslides mentioned Rule # 6 because it is forum policy not knowingly to help with any problem that counts towards a final grade. Whenever the words "homework problem" appear in a post, I always wonder if the homework is for a grade or not. This question must be resolved before you get any help. That you're asking for help on a math problem in a math help forum is irrelevant. Rule # 6 always applies on every single post, private message, and visitor message (and any other form of communication possible) on this forum. Period.

Quote:

I am asking the same question just solved two ways. Rule #8 doesn't apply.
I'm comfortable with the number of questions in this thread.

Quote:

I wasn't aware I needed to include my work toward a solution to get help.
In order to post a thread on this forum, you had to register. In order to register, you were presented with the forum rules to which pickslides linked. Therefore, you should have been aware of this rule.
• Apr 12th 2011, 06:54 PM
Alpina540
It's not for a grade (but I can't prove its not for a grade).

Moderator edit: I have no problem with help being given to the posted question.
• Apr 12th 2011, 07:14 PM
pickslides
Quote:

Originally Posted by Ackbeet
I always wonder if the homework is for a grade or not.

I also wonder this. Before the OP edited the original post there was a reference to a due date, therefore it is not unfair to assume it could be an assessed piece of work.

Quote:

Originally Posted by Alpina540

Sorry to rock the boat, I just thought I might find assistance on a math problem on a math help forum, I guess I was under wrong impression.

I wouldn't say you have rocked the boat much at all. The older members on this forum are actively more aware of the rules than newer members. You have been a member for nearly a year with more than just a handful of posts. Probably well above the median. I can appreciate you are a valid member not just flying past for a quick fix.

*pats on back*

My advice would be to include your working with the initial problem and not to mention due dates. This always arouses suspicion.
• Apr 12th 2011, 07:31 PM
Alpina540
Ok will do from now on.