MEI OCR Mechanics 3, 23rd May 2014

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This is the official thread for the MEI OCR Mechanics 3 paper to be sat on 23rd May 2014.

Reply 1

abdcefghi

It's on the 22nd of may :')! Could've saved your a level there :wink:

Reply 2

george1996:)

Hope the SHM question will not be too hard!

Reply 3

abdcefghi

Yeah I hate shm, everything else is so much easier :')

Reply 4

zsbc123

That exam was sooo horrible, ran out of time and couldn't do most of the elastic string question :frown:

Reply 5

googlebotsgoogle

OP

There was only one question on SHM :biggrin:

Reply 6

george1996:)

Question 4 I couldnt do part i to make it look like there answer and I gave up on question 3 :frown:

Reply 7

george1996:)

questions 1 and 2 were ok though but i know ive lost at least 25 marks :frown:

Reply 8

BoigaDendrophila

2

Was a bugger this exam, I managed to have a good crack at it but dropped about 6 marks straight away. Not a nice exam and question 4 was so long winded and awkward with the algebra. What did people get for the magnitudes of acceleration. O.53 something and 2??

Reply 9

googlebotsgoogle

OP

Original post by BoigaDendrophila

Was a bugger this exam, I managed to have a good crack at it but dropped about 6 marks straight away. Not a nice exam and question 4 was so long winded and awkward with the algebra. What did people get for the magnitudes of acceleration. O.53 something and 2??

I got 2ms^-2 up the slope and some number down the slope (deceleration) for the other part.

Yes!

I got -2.58 for the acceleration at B

(so magniture of 2.58 down the plane)

Reply 12

dznik

Original post by arkanm

Yes, and the smaller one was negative.

Left out the "find

\lambda

" part though.

Time limit should be at least 2 hours IMO.

'Find lambda'?? what bit was that lol

Reply 13

BoigaDendrophila

2

Yep

I managed to find it, came out as 30.7 or something like that, can't remember now really. Wasn't as pushed for time in this as I was for m2 though

Reply 14

dznik

oh ok, could you please explain how you got your value of the acceleration at B? I've checked my workings again and keep getting -2.58

Reply 15

dznik

At B, I calculated the tension to be (37.73/2.2)*0.3=5.145N

resolving parallel to the plane: 5.145cos(theta) - 9gsin(16.3) = 9a

where theta was 90-16.3 =73.7

Reply 16

dznik

Oops i realise what i did wrong, forgot to include the 18N force

Yep

Shouldn't work be on the other side of the equation? I forgot to include it at all... Damn!!! That went so badly!

Reply 19

zsbc123

Yes, it made sense to me that way too. But I kept getting questions wrong, and someone told me to think of it like energy at the start equals energy at the end. That amount of energy has only been transferred after it has stopped moving.

MEI OCR Mechanics 3, 23rd May 2014

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