edexcel maths, units in mechanics

do we need to include units in mechanics? if i decide to include units should i leave them in the bracket to avoid confusion?

Just don’t put units is the safer option, units are never required in the exam and an examiner should ignore them but you never know whether a harsh examiner would mark it wrong if they felt that because you got the units wrong it shows a lack of understanding. Just don’t put them. Always remember to put every answer to 3s.f. you will lose the last accuracy if you are over accurate, and this is still the same if you get; a surd in core maths you would leave it as a surd since it’s exact but in mechanics you should write the surd down then write an extra line with the surd wrote to 3s.f.; if you get an integer like 7548N then you need to still write it to 3s.f. So 7550N people tend to lose the last accuracy mark on ones like this the most because they go “well that’s a nice integer answer” so leave it... just no! Always write to 3s.f and don’t put units.

Post #2 is completely wrong. Units can be required in the mark scheme, and if you understand the content, you should be able to figure out what the correct unit for your answer is. There should not be any "confusion" as this is really quite basic.

Hi so before you start saying I’m wrong, are you an examiner? because I’ve also asked a senior examiner about this before and they have said not to put units for M1. I will say to the person who original asked the question you can feel free to listen to who you want but if you put units that’s fine just don’t get them wrong but you are only adding a stress to your own situation as they are not needed.

Might depend on exam board? Pretty sure I've seen a mark scheme that wanted units - but nonetheless units are extremely easy. The only ones you need really for M1 are ms^-1 ms^-2 N Nm, and there's not much else. M1 is pretty darn straightforward.

sorry to ask what exam board is this from?

Might depend on exam board? Pretty sure I've seen a mark scheme that wanted units - but nonetheless units are extremely easy. The only ones you need really for M1 are ms^-1 ms^-2 N Nm, and there's not much else. M1 is pretty darn straightforward.

Edexcel - but I'm assuming you're on a different exam board since Edexcel's M1 has already been sat

Yeah nah I'm looking at M2

the situation is that if the question asks to find out the value of u, i assume you don't need a unit for that because its just a value. if they ask you to find out the speed after collision for instance, then i feel like its essential to include unit but should I include the unit on the same line as my answer or the line after my answer?

sorry to ask what exam board is this from?

Hi so before you start saying I’m wrong, are you an examiner? because I’ve also asked a senior examiner about this before and they have said not to put units for M1. I will say to the person who original asked the question you can feel free to listen to who you want but if you put units that’s fine just don’t get them wrong but you are only adding a stress to your own situation as they are not needed.

E.g. Edexcel says "Omission of units or incorrect units is not usually counted as an accuracy error", meaning that sometimes it could be counted as an accuracy error leading to loss of a mark.

Also try telling anyone who e.g. works at NASA that "units are not needed" - they lost over $125 million when the Mars Climate Orbiter was lost in 1999 because various teams weren't clear about whether they were using metric or imperial units. Similarly in 1983 an Air Canada aircraft almost crashed because a unit conversion error meant that it took off with only half the required quantity of fuel.

also if they don't give unit in the question then i shouldnt create one right?

In mechanics units will usually be given in the question, but if they're not (e.g. with centre of mass/lamina problems where it doesn't matter what unit the mass is in), then yes, just leave the answer without units.

Not sure if you have realised but he/she doesn’t work for NASA and is sitting his/her Alevel’s and therefore things are best kept as simple as possible because it’s when you over complicate things that you lose marks at Alevel. And thank you for clearing that you are not an examiner and therefore had no right in saying that I was incorrect before. Please know to only give advice when you are sure in your answer and don’t discredit people’s answers who have more understanding of mark schemes than you.