AQA Physics Unit 2 - Unofficial Markscheme

22m/s^2 isnt the answer for the last question. The formual to find out acceleration is resultant force/mass. And in the question it said the upthrust force was 1850N, but that dosent mean that it is the overall force acting on the object. You'd have to also take account in the force going the opposite direction which is the weight of the person and the jetpack which is 840N. You then fidn the resultant force by doing 1850-840 which is 1010N. So the resultant force of the object is 1010N. You then do 1010/84 which is the mass of the jetpack and the person which igves you an answer of 12 m/s^2. Hope you understand how 12 is the answer not 22 .

Yeah, I figured.

I am pretty sure they said they added 1850 N, and anyway, that was a 2 mark question and you got one mark for the units; they wouldn't give you just 2 marks for calculating a resultant force and substituting it into F=ma and the units.

Well said.

Well said.

I could have sworn it was 3 marks.... Also, because there is so much ambiguity, AQA will probably have to be a little lenient. I really don't think the paper made it clear enough whether this was the resultant force or not. Plus, the question on the pull-ups was actually 3 marks (not 4 I don't think) if I remember correctly...., and you had to use 2 equations. Anyway I'm sure it will all be fine!

You're weight or mass can't remember if the force DOWNWARDS, if you life yourself upwards, it doesn't add on. You had to take the downward force off the upward force to get the total force upwards else your calculation will be wrong.
Also a lot of 3 markers this year were complicated for 3 marks so that isn't correct

Well said.

This was in P3 but what did you guys put for the resolution

0.01 and then a unit - I can't remember what!

Bulbasaur, use razor leaf.

thanks for everyone helping me fill it in
has anyone got any ideas what the questions with the answer of 0.015A is?

You're right in everything you've said. Btw for the question on the resistor, I put 600 ohms, but then did some maths as reasoning. Will it count?

I am pretty sure they said they added 1850 N, and anyway, that was a 2 mark question and you got one mark for the units; they wouldn't give you just 2 marks for calculating a resultant force and substituting it into F=ma and the units.

It should do as long as it makes sense. For example, when the resitance of the variable resistor was 200 ohms, the P.D. across it was 3V. Therefore, the current was 0.015A. Since current is the same in a series circuit, and the P.D. over the fixed resistor was 9V, the resistance was 600 ohms. I don't see how they couldn't give you the marks for something like that if it makes sense.