The Edexcel M1 (16/05/12 - AM) Revision Thread

By writing 30 − F = 120sinα, (i would write 30 − 120sinα = F), your F would be negative, but that is because force is a vector, it has direction, as you are solving upwards and F acts downward, this is why your F is negative.

What is a bearing and how do I work it out?

That is what I thought as well but in the answer it says F acts upwards which I don't understand.

What is a bearing and how do I work it out?

Just remember when solving bearing you go from north ( bearing 000 ), you then continue going round ANTI-clockwise, till you hit the vector.

you will sometimes have to use tan to first resolve an angle, the subtract 90 or 180 to find a bearing, DRAW a sketch, it makes it so much easier.

Hey everyone. I have gotten myself into such a state this morning over M1, I am uber stressed as I really really don't like this module and find it so difficult I am not a physics student either, there only three of us not doing physics in my FMaths class and we tend to struggle the most.

Does anyone here do Solomon papers? I tried one this morning and couldn't even do the first question, that really got me down. But yesterday I did one and got 43/45, I have no idea how!?

Quick question, how do you prove that two objects moving in straight lines do not meet (vector question)? I would do it by using the distance vector between them at t hours/minutes/whatever and setting both the i and j components to zero, then working out values of t for each one. If t is not the same for the two components, they don't meet. Is this right/acceptable?

Yeah, I would do it by equating the i and j components seperately and solving the equations simulataneously. If they meet there will be one (or more) solutions

Edit:

Don't worry, Solomen papers are harder/different to the Edexcel papers - I find a lot of the questions hard at first on them

Cool, thanks! And I find Solomons have bizarre 'explain' questions as well, I did one yesterday which asked about a car towing a caravan. The question asked me to explain why my calculated time for the caravan to stop after the towbar broke was possibly unreliable, their answer was that the caravan will 'dip downwards'

Is everybody ready for the exam tomorrow?

Don't worry those Solomen questions are a bit silly really.

If you don't use it already check out examsolutions - it's really good for going over harder questions like the ones in the 08/09 paper. Good luck for tomorrow

If the string is LIGHT (no mass), does it mean that the TENSION is the same throughout, or the ACCELERATION is the same throughout the string?

If it is light it just means it's mass is negligible compared to the rest of the masses and can taken = 0 (ie. ignored)

If it is a light inextensible string the tension will be the same and both particles move with the same acceleration

Ok basically, for b), you find a P of 120N (in equilibrium), so if P is smaller, then the particle will roll down, that is why F acts upwards.

So coming back to this: 30+ F =120sinα OR 30 − F = 120sinα.
We know that the weight is acting down, and P and F both act upward, so you set up one of the equations above and solve for T.
The reason that there are two equations is that, when starting the question you don't know what direction F is acting, so both are acceptable,
If you resolve as down being positive, you will find F being negative, meaning it acts up.
If you resolve as up being positive, you will find f being positive, meaning its acts up

Just remember when solving bearing you go from north ( bearing 000 ), you then continue going round ANTI-clockwise, till you hit the vector.

you will sometimes have to use tan to first resolve an angle, the subtract 90 or 180 to find a bearing, DRAW a sketch, it makes it so much easier.

HUH??? I thought it was clockwise