Question

This is probably easy for some of ya but I just don't understand word problems.. so help please? :)

Free Undamped Motion

Answer 1

A mass weighing 4 pounds is attached to a spring whose spring constant is 16 lb/ft. What is the the period of simple harmonic motion?

Answer 2

Isn't there supposed to be some kind of formula?

Answer 3

I know one just not sure about it.

Answer 4

\[F = k \times x\]

Answer 5

Force = Spring Constant times Displacement, is that right? I am also not sure. :P

Answer 6

That's part of the formula

Answer 7

Not sure. There's a different one I know. Just a sec. Let me type it out. Gawd. My brains will be fried by the end of the dayXD

Answer 8

\[\frac{ d^2x }{ dt^2 } + \omega^2x = F _{0}\]
This may seem confusing.....

Answer 9

Yes, that one ^

I'm just having trouble plugging in the information..

Answer 10

Yay! I got it!! I'm so proud of myselfXD Anywho..Lets see where everything goesXD

Answer 11

Just doing this one for myself only, don't look at it. :P
\[X(s)[s^2 + \omega^2] = F(s) \\ \frac{X(s)}{F(s)} = \frac{1}{s^2 + \omega^2}\]

Answer 12

My phone does not have this option.. :P

Answer 13

LOL. Quit spamming this question. I'm thinking........@e.mccormick shall know:P

Answer 14

That didn't work well. @e.mccormick

Answer 15

Is not the equation supposed to be:
\[M \frac{d^2x}{dt^2} + kx = F\]

Answer 16

Nice try @YanaSidlinskiy

Answer 17

Yea, but we divided by m to make it \(\Large x''+\omega ^2 =0 \)

Where omega is just a sub for k/m

Answer 18

*x

Answer 19

I think then omega is sub for root(k/m) and not simply k/m ?

Answer 20

Then it should be simple I guess..

Answer 21

Eta, there's a thing called where "we all make mistakes, So *******:) " Stop spamming the post, Eta ;) Lets get to work. This is gonna be fun.

Answer 22

My textbook gives me \(\Large \frac{d^2x}{dt^2}+\omega ^2 x=0 \) So I'm just following the book :P

Answer 23

\[\omega = \sqrt{\frac{k}{m}} = \sqrt{\frac{16}{4}}\]

Answer 24

Why are you so serious yana?
If question is a fun, then you can solve it by having fun too. :)

Answer 25

You just need to adjust units now..

Answer 26

Oh, what else does the book tell you? I'm sure there's some answers in the back of the book. Also try and look at the practice problems if it gives you any. I'm sure it does. Eta, it's sarcasm ;)

Answer 27

Yeah, I know, never to argue with girls, at the end, you are gonna lose..!!

Answer 28

the period they give is \(\Large \frac{ \sqrt{2} \pi}{8} \)

Answer 29

So wait. Which formula are we using? And Luigi, so what does 2 and 8 stand for? My brains are fried already, LOL! Eta,

Answer 30

Sorry, but what is relation between lbs and pounds?

Answer 31

You guys confuse me more -.-

Let's see if @hartnn is alive to help :3

Answer 32

lb is short for pounds

Answer 33

Oh..!!

Answer 34

Ya, It's for pounds. Like how much you weigh;) Hah! @hartnn ova here.

Answer 35

period is 2pi/omega

Answer 36

i see we don't get omega as 8 sqrt 2
hmm

Answer 37

How come units of Spring constant is pounds/feet?

Answer 38

I think, it must be Newton/feet or Newton/Meter in SI..

Answer 39

Cause this is America xD

Answer 40

k = mg/L , since we don't have L, this is not useful...

Answer 41

Maybe @ganeshie8 might know?

Answer 42

they told me to use \(32 ft/s^2 \) for something but I don't remember what

Answer 43

that is for 'g'

Answer 44

That is g I think..

Answer 45

g has SI units of m/sec^2

Answer 46

Oh, I think now I got it.. :P

Answer 47

"weighing 4 ponds"!

Answer 48

so thats mg
mg =4

Answer 49

find m from here

Answer 50

use m = 4/32 = 1/8 and try again?

Answer 51

you'll get it :)

Answer 52

mg = 4? are you sure?

Answer 53

yes :)
weight is mg
mass is m

Answer 54

:)

Answer 55

I am sure Lui can do all the substitutions and get his correct answer :)

Answer 56

Finally, got it.. :P

Answer 57

It took me awhile but I finally figured out what you meant, thanks guys for all your time and help :)

Answer 58

welcome ^_^

Answer 59

:) Yw.XD

Answer 60

\(\dagger\)