Here's the question you clicked on:
zerosniper123
I'm completely lost...can someone show me the steps on how to solve these... A force of 750 pounds compresses a spring 3 inches from its natural length of 15 inches. Find the work done in compressing the spring an additional 3 inches.
work done force * distance.
lol forgot that equal after work done.. *work done =force * perpendicular distance.
Okay well can you help me start up the equation because I'm completely lost...:O
it has told u 750 is the force which is not going to cahnge .. so now u just have to find the distance the spring is going to compressed.
|dw:1363361078018:dw|
which is prolly redundant information, we already know the force and the distance that it moved.
.... an additional 3 inches eh we would need to recalculate the Force then right?
\[750=-k(3)\] \[\frac{750}{3}=-k\] \[F_{new}=\frac{750}{3}(3+3)\]right?
since the force to move the spring varies across its distance, we could use integration to determine the total amount of work done .... if you believe that the question is asking for a more complicated result
\[W=\int Fxd\] \[W=\int_a^b(-kx)x~dx\] \[W=\int_{3}^{6}\frac{750}{3}x^2~dx\] \[W=\frac{750}{9}(6^3-3^3)\]
Okay and that is the work done :) Thanks man! :D
Why is W= 750/9 shouldnt it be 750/3?
then times by (6^3-3^3)
no, you are prolly not familiar with integration if you ask that question
Okay...What exactly are the units?
in effect: to integrate a variable, you want to increase the exponent by 1, and divide by the new exponent \[\int~x\ dx=\frac{x^2}{2}\]
Ohhh okay thanks. :)
the units will still be pounds per inches
pounds per square inches that is
Okay thanks man! :D
So 15,750 pounds per square in.
Force over a Distance .... nah, its just pounds per inch you might want to make it more presentable tho and convert it to Newtons of something
Okay so how would I change it to N ewtons?
conversions arent in my memory .... might have to google a conversion :)
Okay thanks anyways! :D
Work is normally expressed in Newtons per meter
so newtons to pounds and inches to meters would be the conversion
Yeah it gave me this 2758247.65125 per Newton Meter
http://www.convertunits.com/from/pounds+per+inch/to/newton/metre
Thats the website I used to convert.
\[\frac{1575lbs*in}{1}\frac{.0254m}{1in}*\frac{4.448N}{1lbs}=177.94~Nm\]
my mistake was in the lbs/in,,, its lbs x inches
Okay so its x not *
more like: \[\cancel{\frac{1575~lbs}{1in}}\to1575~lbs~in\] "per" is divisiion and we didnt divide .. we multiplied
lol .... and i seemed to have dropped a 0 on the end, 15750
Haha okay thanks :)
So the answer is 17,794.2Nm ;D