Here are some questions I am stuck on. Hope you can answer them.
Show that the pressure exerted by a 2.5kg brick when sitting on its largest face (area 20 x 10-3m2) is about 1.25kPa. Thus show that if the maximum compressive strength of common bricks is 20MPa, the maximum height of a stack of bricks, before the bottom gives way, is about 16km.
Show that a nylon fishing line of diameter 1mm requires energy of the order of 1mJ to fracture and that, assuming the average value for the tensile strength of nylon, this corresponds to a load of about 400N.
A piece of rubber 6cm long cut from a rubber band will easily extend to 7cm when supporting a small load. Bonds between atoms typically break when the distance between the atoms is increased by 1%. Show that the extension of the rubber cannot simply be due to stretching of the bonds between atoms.
Hooke's law states that extension is proportional to load F and is usually written F=kdeltax. The Young modulus E=stress/strain. Show that the Hooke's law constant k is related to the Young modulus E by the relationship k=EA/L
AS Advancing Physics - Looking inside materials questions Watch
- Thread Starter
- 31-03-2013 21:11
- 31-03-2013 22:23
Could you take a look at the guidelines for posting questions here
In particular the following
... when posting include any progress you already have towards it. What we would not like you to do when posting is to post in a manner that suggests you want other people to do your work for you, which is also likely to lead to you not getting the responses you would like.
-post one question per thread
-show what attempt you've made and where you are stuck