Skip to main content

Use Hooke's Law to determine the variable force in the spring problem. An overhead garage door has two springs, one on each side of the door. A...

As the problem stated, we first need to figure out the spring constant.  Hooke's Law says that the spring constant can be calculated by dividing the force by the distance of movement.  It takes 15 pounds of force to move the spring 1 foot, so the spring constant is 15.  


A stretched spring has elastic potential energy.  The potential energy that is stored in the spring is equal to the work done to stretch the spring in the first place.  That means the potential energy in the spring is equal to the work that the spring can do; therefore, calculating the spring's potential energy will give you the work done by the spring when the door opens.  


The formula for calculating a spring's potential energy (work) is PE = (kx^2)/2. K is the spring constant.  X is the total movement of the spring from its rest position. The door moves a total of 8 feet, and the problem stated that the springs move half that distance. 


(15 x 4^2)/2 = work


(15 x 16)/2 = work


240/2 = work


120 foot pounds = work


Remember, there are two springs both doing the work, so the answer needs to be doubled.  The total work being done by the springs is 240 foot pounds. 


One last detail.  The work is technically a negative number (-240 foot pounds) in this case.  That's because the motion of the springs is opposite to that of the garage door. 

Comments

Post a Comment

Popular posts from this blog

Is there a word/phrase for "unperformant"?

As a software engineer, I need to sometimes describe a piece of code as something that lacks performance or was not written with performance in mind. Example: This kind of coding style leads to unmaintainable and unperformant code. Based on my Google searches, this isn't a real word. What is the correct way to describe this? EDIT My usage of "performance" here is in regard to speed and efficiency. For example, the better the performance of code the faster the application runs. My question and example target the negative definition, which is in reference to preventing inefficient coding practices. Answer This kind of coding style leads to unmaintainable and unperformant code. In my opinion, reads more easily as: This coding style leads to unmaintainable and poorly performing code. The key to well-written documentation and reports lies in ease of understanding. Adding poorly understood words such as performant decreases that ease. In addressing the use of such a poorly ...
Post a Comment
Read more

Is 'efficate' a word in English?

I routinely hear the word "efficate" being used. For example, "The most powerful way to efficate a change in the system is to participate." I do not find entries for this word in common English dictionaries, but I do not have an unabridged dictionary. I have checked the OED (I'm not sure if it is considered unabridged), and it has no entry for "efficate". It does have an entry for "efficiate", which is used in the same way. Wordnik has an entry for "efficate" with over 1800 hits, thus providing some evidence for the frequency of use. I personally like the word and find the meaning very clear and obvious when others use it. If it's not currently an "officially documented" word, perhaps its continued use will result in it being better documented.
Post a Comment
Read more