dino's questions leading up to unit 3 exam, 2009.

[toomoo]

When you see questions like this in the exam tomorrow a smile should come to your face.
marks for jam.

[dino]

I hope so. this is going straight to the cheatsheet.

[arthurk]

can someone confirm that the answers for question 3 are indeed B as the answer says
or is it A like kamil and i thought

[vamsiaus]

yea just checked the answers, the answer for q3 was B not A. It is DOWNWARDS not upwards.

[arthurk]

can u prove it for me please^^

[kamil9876]

oh shit yes you are right, it is A, because the question says 'roof beam applies to the wall'. we found 'wall applies to roof beam' and so that is upwards, however 'roof ebam applies to the wall' is in the opposite  direction of that by Newton's third law.

SOrry, I read it too quickly

[arthurk]

LOL
haha it seemed like a good plan at the time
seemed to fit in with every other question that followed it

[kamil9876]

opps and i made two small arithmetic mistakes in question 4:

I had '2' instead of 2.5 for some stupid reason  :idiot2: It should be:



ALso I forgot the g in my latter equation:

15-2.5F=0

It should be:

30g-2.5F=0
F=12g

The 30 comes from the first correction.

Very sorry about that, but I hope you at least you understood the general idea