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physics formula

if i put down tensile stress = young modulus x tensile strain
as stress = F/A
The question wanted F.
I crossed out stress, Put F there, and put X A on the right.

The mark scheme shows
tensile stress = young mod x strain
stress = F/A
----- (2 marks)

As i crossed out stress that is visible to see and put F there, would i be still allowed the mark you think?
Reply 1
Avatar for 0le
0le
21
I'm not sure what you are asking. Force/area is a general equation valid for an applied stress. That stress can be shear or tensile.
Reply 2
Avatar for Batman2k1
Batman2k1
OP
14
Original post by 0le
I'm not sure what you are asking. Force/area is a general equation valid for an applied stress. That stress can be shear or tensile.

I did alevel physics aqa test.
Would i be allocated the 2 marks?
You needed to show the two formulae of tensile stress and young modulas.

The question wanted to find out the force, F.
So what i did was a shortcut. Just cross stress out, (F/A), so i put F on the LHS and A on the RHS.

So i am confused whether this is acceptable. It's sort of like simplifying my working, like 2/4 = 1/2, but i cross the 2 and 4 out, and put 1 and 2 there.
Reply 3
Avatar for 0le
0le
21
Original post by Batman2k1
I did alevel physics aqa test.
Would i be allocated the 2 marks?
You needed to show the two formulae of tensile stress and young modulas.

The question wanted to find out the force, F.
So what i did was a shortcut. Just cross stress out, (F/A), so i put F on the LHS and A on the RHS.

So i am confused whether this is acceptable. It's sort of like simplifying my working, like 2/4 = 1/2, but i cross the 2 and 4 out, and put 1 and 2 there.

I mean yeah, the algebra is obvious, you just didn't write it out explicitly. In my opinion, it shouldn't normally be a problem but you shouldn't give the exam board any reason to drop marks. In the future, write each line out explicitly.
Reply 4
Avatar for Batman2k1
Batman2k1
OP
14
Original post by 0le
I mean yeah, the algebra is obvious, you just didn't write it out explicitly. In my opinion, it shouldn't normally be a problem but you shouldn't give the exam board any reason to drop marks. In the future, write each line out explicitly.

Oh okay, thanks 0le.

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