Can anyone define the strength of a material, for example on a stress/strain graph or force/extension graph. What would show that the material is strong?
For questions on moments, will we be told what points to take moments about? If not how do we know where to take the moments about? Also, does the weight of an object that acts at the centre always provide a clockwise moment?
Can anyone define the strength of a material, for example on a stress/strain graph or force/extension graph. What would show that the material is strong?
With the parallel and series spring, I always explain it mathematically,
Series: Force is the same, extension doubles (as you have twice the spring), so spring constant must be half to obey Hookes Law. ( F= (K/2)*(2E) )
Parallel: Force is the same, extension half ( as you have they are side by side ) , so spring constant must be double obey Hookes Law. ( F=(2k)*(E/2) )
Simplifying both variations give you F=kx.
Hopefully that's an accepted answer, its got something along those lines in the jan 2012 markscheme.
With the parallel and series spring, I always explain it mathematically,
Series: Force is the same, extension doubles (as you have twice the spring), so spring constant must be half to obey Hookes Law. ( F= (K/2)*(2E) )
Parallel: Force is the same, extension half ( as you have they are side by side ) , so spring constant must be double obey Hookes Law. ( F=(2k)*(E/2) )
Simplifying both variations give you F=kx.
Hopefully that's an accepted answer, its got something along those lines in the jan 2012 markscheme.
For questions on moments, will we be told what points to take moments about? If not how do we know where to take the moments about? Also, does the weight of an object that acts at the centre always provide a clockwise moment?
It always tells you where the pivot is ^_^ And i'm not sure on the 2nd part I could do with knowing that actually
For questions on moments, will we be told what points to take moments about? If not how do we know where to take the moments about? Also, does the weight of an object that acts at the centre always provide a clockwise moment?
It depends, just visualise it, if the centre of gravity is on the left of the pivot, it will be anticlockwise. If it's on the right it will be clockwise. But it really depends on the question.
It always tells you where the pivot is ^_^ And i'm not sure on the 2nd part I could do with knowing that actually
Yeah but i was doing some older papers where they didn't tell you the pivot where they gave you two forces and the weight and you had to determine where to take moments about to find one of the forces. So was curious as to whether we might have to do the same in these papers