Wednesday 16 November 2016

Introduction of Hooke's Law

Tai Wei Zhun (28313593)
Introduction

Hooke's Law is a law of mechanics and physics by Robert Hooke. The theory states that, if the load does not exceed the material’s elastic limit, the force needed to extend or compress an elastic object such as spring is directly proportional to the extension.





Hooke’s Law equation:

F=kx

where,

F = force applied on the elastic object (N)

k = spring constant (N/m)

x = the length of extension / compression  of a spring (m)

*Hooke’s law applies, as long as the material is within it’s elastic limit.





Experiment
          
           Fig1

Method:

    1)     Set up the apparatus as shown in Fig 1.

    2)     The spring to be tested is fixed at one end of the clamp, hanging parallel with the ruler (meter stick).

    3)     A known force is applied to the material, causing it to be displaced.

   
   4)     The displaced length is measured and recorded.

    5)     Steps 3 to 4 are repeated 9 times, each time applying a greater force.

    6)     This experiment is repeated 2 times with 2 other different materials. (total three different materials)
                 



Result

The results of the experiment are shown below.

y1, y2 and z is the extension of material 1, 2 and 3 respectively.



Deformation of y1:

The equation for deformation y1 is given as : y1 = ax+b

Fig 2. Deformation of y1



By using the result in Fig 2, a graph of Force Applied(N) versus Deformation of y1(mm) is plotted.



Fig 3. Deformation of y1 against force applied




From the graph in Fig 3, we can obtain the value a and b from the equation .

Since  y1 = 1.5583x+1.375    

So   a = 1.5583    and    b = 1.375 





Deformation of y1 and y2


The deformation of y2 is given as : y2 = (a+0.5)x + c, where c = 0.2



Fig 4. Deformation of y1 and y2


By using the result in Fig 4, a graph of Force Applied(N) versus Deformation of y1 and y2(mm) is plotted.



Fig 5.  Deformation of y1 and y2 versus force applied


From the graph above, line of deformation y2 has the equation : y2 = 2.0583x + 0.2 



The line of best fit was plotted, the lines indicate the relationship between the force applied (N) and the deformation of y1 and y2, which is directly proportional to each other. As the force applied increases, the deformation of y1 and y2 increases.



Line of deformation y2 has a greater gradient compared to line of deformation y1 shows that material y1 is stiffer compared to material y2. 



Based on Fig 5 , the meeting point of y1 and y2 is estimated as (2.10, 4.90)

The actual meeting point is calculated by resolving the simultaneous equations:

y1 = 1.5583x + 1.375 ---- 


y2 = 2.0583x + 0.2 ---- 


 


=


1.5583x + 1.375 = 2.0583x + 0.2


0.5x = 1.175 


x = 2.35


 


When x = 2.35, 


y = 2.0583 ( 2.35) + 0.2 


y = 5.037 


Therefore the meeting point  is ( 2.35, 5.037)



Deformation of z :
The equation of deformation Z is given as : z = x³+ b, where b = 1.375

 


Fig 6. Deformation of z



By using the result in Fig 6, a graph of Force Applied(N) versus Deformation of z(mm) is plotted.



Fig 7. Deformation of z


By analysing the graph above, the line of Z has the equation :

 


 


Conclusion


Based on the experiment, the results obtained shows that the force applied is directly proportional to the extension of the spring within the elastic region.

However material z not show this result as it already into plastic region.

Thus it shows that Hook’s Law is true, if the load does not exceed the elastic limit.


Since the experiment is conducted, there are a few errors that  can be improved :

1) Parallax error


    - setting our eyes perpendicular to the metre ruler while taking reading 



2) Inaccurate results obtained


   - repeat the experiment at least twice 


 






References


- Hooke’s law – Wikipedia, the free encyclopedia. 2016. Hooke’s law – Wikipedia, the free encyclopedia. [ONLINE] 



[Accessed on 16 November 2016]


- What is Hooke's Law? - Khan Academy [ONLINE]


https://www.khanacademy.org/science/physics/work-and-energy/hookes-law/a/what-is-hookes-law


[Accessed 16 November 2016].


 



- Hooke's Law Experiment - Stretching Springs - Cyber Physics [ONLINE]


http://www.cyberphysics.co.uk/topics/forces/hooke.htm


[Accessed 16 November 2016].




- Hooke's Law Experiment - TutorVista [ONLINE]


http://www.tutorvista.com/physics/hookes-law-experiment

 

[Accessed 16 November 2016]

Thursday 13 October 2016

Googling Myself

Googling Myself

Why do you think were there so many or so few hits about you?
Ans: There are 2 links that hit about me and I think there are so many. This is because I am not a famous people.

Would you prefer to have more or less hits, and why?
Ans: I prefer to have less hits, cause I am shy to let too much of people to know about me.

What might the benefits of having lots of hits on Google be in the future?
Ans: The benefit of having lots of hits on Google be in the future are they can be easier to search for my information and this will lead me become famous in future.

What potential downsides are there to having many hits on Google?
Ans: The potential downsides are it might make people lost their privacy and not be so free in future.

Explain why your Google-presence may help or hinder you getting a job after your degree.
Ans: It can let the company that desire for a person who have ability much easier to find me. Thus I can get a job easier.


Facebook

What information is available on this public profile? Are there photos visible? Are your interests visible?
Ans: There are a lot if photos.

What makes you uncomfortable about the visibility of this information, and why?
Ans: I feel very comfortable cause it only shows what I want to show.

Explain why you would be happy/unhappy for a potential employer to see this page.
Ans; I am happy for a potential employer to see this page because they can know me well as they want.


Reppler

How many "Inappropriate Content" alerts did you receive?
Ans: zero!

Why do you think Reppler flagged this content as "inappropriate"?
Ans: I have zero inappropriate content.

How would you explain this content to a potential employer at interview?
Ans:I really don't have any inappropriate content. Trust me!!!!

How many privacy and security risk alerts did you receive?
Ans: Zero again.

Explain why they are privacy or security risks. How might someone nefarious use this information to harm or inconvenience you?
Ans: I don't have post any privacy things that can let nefarious to harm me. HAHAHA I am safe!




Facebook Friends

The Faces of Facebook doesn't work.

How do you think Facebook calculates this?
Ans: It depends on how many chats that you chat with him.

Do any of the people at the top of your on the list surprise you? Why do you think they are near the top?
Ans: Not surprise me. Cause I chat with her everyday.

Would you be happy or unhappy to show this list to your Facebook friends, and why?
Ans; I am unhappy to show this list to my Facebook friends because this is my privacy.



Privacy settings and tidying up

What group of people can see posts that you make in the future?
Ans: Friends.

If it is public, are you happy that everyone on Facebook can potentially see everything you write?
Ans:Ya ! I am happy.

If it is Friends of Friends, what are the implications of posting to a relatively large group of people that you may not know?
Ans: That will lead me in a dangerous situation cause somebody that admire a for a long time can find me more easier.

Who can look you up and can search engines link to your Timeline? Who could potentially see your Timeline if this is set to On?
Ans: My friends! Search engines can link to my Timeline. My friends can see my Timeline.





How many apps are listed as having access to some or all of your data? How many do you remember authorising?
Ans:15 apps. All

Do you trust all of those applications to use your data responsibly? Why?
Ans: Trust! They are a big company and wont cheat me.

If one of these applications were bought by another company, would you consider removing the app from Facebook? Why?
Ans: No! lazy to do it.