# OCR mechanics M1 22/05Watch

This discussion is closed.
12 years ago
#21
isn't it 80% to get an A? i can guarantee i lost at least 20%...
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12 years ago
#22
(Original post by Mustard-man)
Can you guys tell me how bad you did so we can sort of see how bad everyone did!!

Just hope that the grade boundaries will be low
I think I lost about 10/12 marks.
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#23
(Original post by graveyarddreams)
isn't it 80% to get an A? i can guarantee i lost at least 20%...
Nope, that's the UMS grade boundary. Last year for M1 an A was 78% for Jan and 68% for June
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#24
(Original post by ironically)
I think I lost about 10/12 marks.
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12 years ago
#25
When finding the angle in (I think) Q5/6. With the block and the force at an agle of alpha...

Did you get: tan(alpha) = 6/5

Or something to that effect.
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#26
(Original post by ironically)
When finding the angle in (I think) Q5/6. With the block and the force at an agle of alpha...

Did you get: tan(alpha) = 6/5

Or something to that effect.
I did get tan(alpha) = something, but not 6/5
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12 years ago
#27
(Original post by ironically)
When finding the angle in (I think) Q5/6. With the block and the force at an agle of alpha...

Did you get: tan(alpha) = 6/5

Or something to that effect.
i can't remember my answer, but yeah it was something like that, it was sin alpha over cos alpha which was tan alpha, so it sounds right.
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#28
I pray to God I didn't made any mistakes, sometimes I lose easy marks just because I made silly mistakes :O
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12 years ago
#29
(Original post by Mustard-man)
Nope, that's the UMS grade boundary. Last year for M1 an A was 78% for Jan and 68% for June
i'm not surprised, june 05 was a very bad paper It took me about 3 hrs to finish it. So what's UMS boundary, does the same apply to other examination boards for other subjects?
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#30
(Original post by graveyarddreams)
i'm not surprised, june 05 was a very bad paper It took me about 3 hrs to finish it. So what's UMS boundary, does the same apply to other examination boards for other subjects?

Well raw marks are converted to UMS marks. The conversion takes account of the difficulty, usually when converting, the marks are scaled up. Maths doesn't get scaled up that much because it's possible to get 100%. In essay subjects you may get 90% in terms of raw marks, but as UMS marks, that could be 100%
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12 years ago
#31
(Original post by Mustard-man)
I did get tan(alpha) = something, but not 6/5
I can't remember it exactly, but was it something like:

F = Pcos(alpha) = 6
N = Psin(alpha) + 2.55g (25N)

And F = mu N
So, N = 6/0.2 = 30

Psin(alpha) + 25 = 30
Psin(alpha) = 5
Pcos(alpha) = 6
- Divide -

Tan(alpha) = 5/6

That's off the top of my head though.
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12 years ago
#32
(Original post by Minthumbug)
i had trouble with Q5, i think it was. where you had to find the coefficient.

did anyone alse get a= -4ms^2?

then 0.98sin15 + friction = 0.1 x -4

or something like that o_O

I got final mu=0.1.. something
I think I got the same acceleration as you. But my coefficient of friction was something crazy like 3.66 or something like that. I've probably failed this paper, or got a really low mark
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12 years ago
#33
Thought there was a mix of OK questions, and some tough ones. I couldn't do the last part of question 3, and I thought the question with P at an angle to a block was tough. I got a pair of answers but am not sure whether they were right (grr, was worth 8 marks).

I got to 1500N at the end of the train question, so I think that one was OK. On question 7 I worked out the coefficient of friction while it was moving, just to be sure that the friction was limiting (so I could use F=uR). I think I got limiting friction to be around 0.4N, and the acceleration in the last part to be about 3 (can't remember to more than 1sf!). What did everyone else get for this question?

Hope everyone gets the grades they want!
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12 years ago
#34
I think I got the coefficient to 0.69 and the final velocity to 6ms^-1
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#35
(Original post by ironically)
I can't remember it exactly, but was it something like:

F = Pcos(alpha) = 6
N = Psin(alpha) + 2.55g (25N)

And F = mu N
So, N = 6/0.2 = 30

Psin(alpha) + 25 = 30
Psin(alpha) = 5
Pcos(alpha) = 6
- Divide -

Tan(alpha) = 5/6

That's off the top of my head though.
I think you're right, I think I was thinking of another question

I can't really remember these questions because I didn't have much trouble with them. I didn't check through them either because I was trying to work out the last 2 parts for q6
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12 years ago
#36
It wasn't too bad until the last question, but I kinda had a problem due to spending too much time on the rest of the paper.

1.
3(1200+m)-3(1200)=5(1200)
3m=6000
m=2000kg

2.
(i)
Resolving horizontally 6.5sin(theta)=2.5

sin theta=2.5/6.5
theta=22.6

(ii) Resolving vertically R=6.5cos22.6
R=6N

3.
I think the the graph went from shallow till t=80 steep for a bit and then shallow again near the end.

(ii)Dotted line was just from start of man to end of man
constant s=2.25t

(iii)
120+4.5t=180+2.25t

4.
(i) integrate v=2
s=2t hence s=20m

(ii) integrate v=0.03t^2 -0.3t+2

s=0.01t^3-0.15t^2+2t+k

place in the value from the start t=10 s=20 to give k=5

(iii) differentiate v=0.03t^2-0.3t+2

0.06t-0.3=a t=5

Sub in t=5
s=0.01t^3-0.15t^2+2t+5

5. mu=0.2

R=mg

5=0.2mg

m=2.55kg

(ii)

Just making it into Tan, I got something like 36.9 or somewhere around that

the value of P I had was 7.81

6.
(i)driving force-15000=80,000a

Driving force needs to be more than 15000 for accel to be +ve

(ii)35000-15000=80,000a
a=0.25

(iii) 35000-8500-10500=(Engine mass)0.25
Engine mass=64,000kg

(iv)
-15000-10500-3000-1500=80,000a
a=-0.375

therefore

F=MA for B

-1500=(B)-0.375
B=4000kg

(v)

(coupling force)-15000-10500=64000*-0.375
-25500+(coupling force)=-24000

therefore coupling =1500N pushing the engine.

Last question...meh

That tan 6/5 I think is right...forgive me if some of that is wrong, since i'm still half asleep from w2 revision....
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12 years ago
#37
Phew!

This was my last chance to retake this bummer module (2nd time now!).
Found this much easier than the last 2 tries. I was suprised that there was no questions on forces in equilibrium, pulleys, strings.

Mainly some resolving and momentum questions, and a easy linear motion question.

However, i didnt have time to do the last question...nor did i know how to do it lol
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#38
bloody hell parrotman, how on earth did you remember??!!
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12 years ago
#39
Meh....i'm sure some of that is wrong....
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12 years ago
#40
found it fairly hard, but easier than june 05.

what time did every1 get for the man overtaking the woman? i got 90 something, i used simultaneous equations, any1 else do this?

couldnt really do the last question, i think i got 0.1 something for the coeffiecent of friction, and maybe 6 for the velocity. couldnt do the last show that something was 1500kg, but the rest i got the same answers as parrottman.
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