I dont get this :/
http://screencast.com/t/eSTW1oOF

Question

I dont get this :/
http://screencast.com/t/eSTW1oOF

anonymous · Answer

answer shuld b 10^2

somy · Answer

woah!! im confused here too T_T

vincent-lyon.fr · Answer

This is really food for thought!

anonymous · Answer

LOL awesome question

$$\delta L = \frac{YLmg}{A}$$

now.. all linear dimensions are  reduced to one tenth

L goes down by factor of 10
length of the cube goes down by factor of 10, (so u can calculate the new mass) 
radius of the wire goes down by a factor of 10 (so u can calculate the new area
and so u can plug in and find the ratio of extensions!

somy · Answer

@Mashy

anonymous · Answer

ohhw :P.. no it should be 100

somy · Answer

why?

somy · Answer

marking scheme is showing B

anonymous · Answer

$$L ' = L/10 \m' = m/1000 \ A'  = A/100$$

so if u plug them in
and find$$\delta L /\delta L'$$

u would get a 100

somy · Answer

man =_= my question is different 
read  it

anonymous · Answer

That is correct..  just plug in stress formula..

somy · Answer

how?

somy · Answer

i just divide all values by 10?

anonymous · Answer

all LINEAR.. 

so lenght and radius goes down by 10
but mass goes down by a 1000... think how

somy · Answer

by 1000????

vincent-lyon.fr · Answer

Mashy is right.
The first answer is 100
The second answer is 10

anonymous · Answer

mass?

anonymous · Answer

@Mashy  Thanks for your work, but we have only learnt the formula E =FL/AX where F = force, L = length , A = area X = extension, we havent learnt anythng about mass :/

anonymous · Answer

i dont understan, how u brought up mass:/

vincent-lyon.fr · Answer

The force exerted by the load is proportional to its mass, its volume, its length cubed.

Hence real force is 10x10x10 times the model-force

anonymous · Answer

how did u gt tht equation>