GCSE Level Questions: Moments and Centre of Gravity
When answering a question that has sub-parts ((i), (ii), (iii) etc.) look at what is needed in ALL parts before formulating your answer.
You will not get marks for making the same point in both parts.
Also reading the whole section of the question helps you understand where the examiner is 'going' with the question.... what information s/he is trying to get out of you for the mark...
General Pointers - Things to think about before attempting these questions
Centre of mass is the same as centre of gravity. It is the point through which the weight of the object acts.
You draw the weight arrow vertically down from that point.
If an object is made up of various parts and you move one of those parts the centre of mass/gravity of the whole thing will move position - and that may affect the overall stability.
NEVER use the word momentum instead of moment – they are quite different!
A point can never be parallel or perpendicular to anything!
A moment has two parts – if the moment is greater that can be due to either part. Therefore if a moment is 'greater' it is wrong to say ‘the force of the moment increases’ unless you are talking about the ‘force part’ of the moment.
A resultant moment will cause an object to turn – a resultant force will produce an acceleration (F = ma) 'm' is the abbreviation for mass NOT the abbreviation for moment!
Always write the word 'moment' for a moment - never abbreviate it to 'm' or 'M' unless your syllabus allows you to do so!