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    would I lose a mark for putting impulse as 3ns-1 rather than 3ns?

    also, would 74 be 100ums?
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    Feeling quite happy, I think I got 65/75

    the only 2 questions that let me down are 7)a) I did it but got the wrong answer and question 3. In total lost 8 marks on these 2 combined and lost another 2 marks down to my incompetence.

    in total (from c1, c2,s1 and m1) I believe I have 350 ums/ 600

    I feel happy
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    I thought I did quite bad in that exam, it was quite weird, but I actually did well for once in Mechanics
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    For the resultant force on the pulley, in the question where it said show the direction that the resultant force makes, I drew a diagram with 45 degrees marked on it but

    Does it matter in which direction you drew the arrow going

    e.g if you draw it going towards the pulley or if you draw it going away from the pulely
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    (Original post by KloppOClock)
    just need to do 2 and 8, but im missing parts of the question
    For the scale pan question:
    A scale pan of mass 0.5 kg is attached to a string. In the scale pan there is a brick of mass 1.5 kg. The scale pan moves upwards with constant acceleration of 0.5 ms^-2. Find:
    a) The tension in the string.
    b) The magnitude of the force exerted on the scale by the brick

    Solution (or at least, that's what I did):
    a) (Upwards):
    T - 0.5g - 1.5g = (0.5+1.5)*a, where a = 0.5
    T - 2g = 2*0.5
    T = 20.6N

    b) Force exerted by brick on scale = force exerted by scale on brick (Action-Reaction principle)

    For brick only:
    Let R be the reaction (i.e., the force exerted by the scale on the brick)
    R - 1.5g = 1.5*a
    R = 1.5*0.5+ 1.5g
    R = 15.45
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    For question 5 (where you had to calculate μ ), how many marks out of 10 do you think it's possible to get if you resolve the 40N force wrongly (I put sin and cos the wrong way round) but all of the method after that is correct?
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    (Original post by iiiii)
    For question 5 (where you had to calculate μ ), how many marks out of 10 do you think it's possible to get if you resolve the 40N force wrongly (I put sin and cos the wrong way round) but all of the method after that is correct?
    youd pick up most of your method marks, but because you made an error at the start you could lose quite a few marks depending on how many a1 or dm1 marks there are.
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    Solution to 8 a
    Attached Images
     
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    (Original post by the___jackal)

    also, would 74 be 100ums?
    not to speculate too much but it could well be, for the last few years the mark out of 75 needed for 100ums has been between 68 and 71 and this paper didn't seem significantly easier than other recent ones to me
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    (Original post by KloppOClock)
    youd pick up most of your method marks, but because you made an error at the start you could lose quite a few marks depending on how many a1 or dm1 marks there are.
    ok great thanks, I'lll just have to wait and see
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    (Original post by KloppOClock)
    ok ive done this twice now (once in the exam, once again now) and ive got the same answer which is different to what I have been seeing.

    V= U + AT
    V = ? U = (3i-22j) A=(3i+9j) T=3
    |U| = root(3^2 + (-22)^2) = root(493)
    |A| = root(3^2 + 9^2) = root(90)

    V = root(493) + 3*root(90)

    V= 50.66410225
    V = 50.7


    anyone?
    You can't do that, the vectors have direction, you can't just do the speed .
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    (Original post by the___jackal)
    Solution to 8 a
    fantastic, ill add that last one in
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    (Original post by KloppOClock)
    I'm trying to do model answers for the questions but I can't find the details of the questions. If you can remember what the question details were then sure.
    q2
    there was a scale pan accelration upwards at 0.5ms^2 with mass 0.5kg and it was holding a crate of mass 1.5kg and it was being pulled up by a light inextensible string

    find the tension of the string
    find the force exerted on the scale pan by the crate
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    Btw the scale pan question couldnt have been 15.5. Because that is the force the SCALE PAN exterts on the BRICK. The question told us to work out the force the BRICK exerts on the SCALE PAN which should be 14.7 right?
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    Estimate for How many marks for taking moments about A&B instead of S&T, then getting the wrong numbers, method marks would be available?
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    (Original post by kprime2)
    I'll be posting model answers tomorrow (edexcel)
    Estimates for grade boundries/UMS?
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    For Question 4.a I got everything correct apart from the fact that I had the T value as more than 25 seconds. How many marks would I lose??
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    (Original post by kprime2)
    I'll be posting model answers tomorrow (edexcel)
    Estimates for grade boundries/UMS?
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    Okay, I've done all the model answers and i've written out every question. its officially complete!






    i have no life
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    (Original post by KloppOClock)
    ALL MODEL ANSWERS ARE NOW DONE!

    IMPORTANT NOTE: After speaking with some maths teachers, they have said that they believe the grade boundaries will be relatively low due to the simultaneous vector question and question three! :banana2:

    *So people stop asking, when using 'g' 2 or 3 significant figures is fine.

    Question 1: (10 marks)
    Spoiler:
    Show
    1(a) 104, (3 marks)

    1(b) p = (400+15t)i + (20t)j (3 marks)
    q = (20t)i + (800-5t)j

    1(c) Q = 640i + 640j (4 marks)

    Model Answer Below
    Question 2: (6 marks)
    Spoiler:
    Show
    2(a) T = 20.6N or 21N (3 marks)
    2(b) 15N or 15.5N (3 marks)

    Model Answer Below
    Question 3: (7 marks)
    Spoiler:
    Show
    3 Ns (7 marks)

    Model Answer Below
    Question 4: (12 marks)
    Spoiler:
    Show
    4(a) (4 marks)

    4(b) T = 8.75 s (8 marks)

    Model Answer Below
    Question 5: (10 marks)
    Spoiler:
    Show
    μ=0.73 or μ=0.727 (10 marks)

    Model Answer Below
    Question 6: (7 marks)
    Spoiler:
    Show
    d = 1.2m (4 marks)
    m = 42kg (3 marks)

    Model Answer Below
    Question 7: (11 marks)
    Spoiler:
    Show
    7(a) F2 = 2.5i + 2.5j (7 marks)
    (b) 13 ms-1 (4 marks)

    Model Answer Below
    Question 8: (12 marks)
    Spoiler:
    Show
    8(a) T = 11.8 N or 12 N(8 marks)

    8(b) = 16.6 N or 17 N
    It has a bearing of 225
    or
    45 degree angle between horizontal plane and vertical rope
    or
    draw a diagram and annotate angles (4 marks)

    Model Answer Below
    Model Answers: (click spoiler to show images).



    Question Bank: (simplified)
    Spoiler:
    Show
    Question One:
    Q has velocity (20i-5j) and starting position (800j). P has velocity (15i+20j) and starting location (400i).

    a) Find the bearing of Q.
    b) i) Find the location of P and Q at time = t.
    c) Find the location of Q when it is west of P.

    Question Two:
    A scale pan of 0.5kg carries a brick of 1.5kg and is attached to a vertical rope. The body is accelerating upwards at 0.5m/s/s.
    a) Find the tension in the rope.
    b) Calculate the force exerted by the scale pan onto the brick.

    Question Three:
    A particle of mass 0.4kg collides with a wall at a speed of 4m/s and rebound back 5m before stopping. The coefficient of friction on the ground is 1/8. Calculate the magnitude of the impulse exerted by the wall onto the particle.

    Question Four:
    A car M overtakes car N at 40m/s at point A and travels for T seconds before uniformly decelerating to 0m/s at point X. Car N travels at 30m/s for 25 seconds before decelerating uniformly at the same point. AX = 975m.
    a) Draw a speed-time graph of both cars on the same graph.
    b) Find the value of T.

    Question Five:
    Particle of mass 2kg on slope inclined to ground at 20 degrees. Being pushed up a rush surface by force of 4 N at angle of 30 degrees to slope. Calculate mew.

    Question Six:
    Non-uniform rod of length AB has length 6m and mass 30kg. It has two supports S and T, where AS = 0.5m and TB=2m. When a particle of mass M is placed at A, the rod is at the point of tipping around S. When a particle of mass M is placed at B, the rod is at the point of tipping around T. The distance between A and the center of mass is D.
    a) Find D
    b) Find M

    Question Seven:
    F1 = (-i + 2j) F2 same direction as (i+j). Resultant of F1 and F2 has same direction as (i+3j). The resultant of F1 and F2 has acceleration (3i+9j) and initial velocity (3i-22j).
    a) Calculate F2
    b) Find the velocity of the resultant of F1 and F2 and t=3.

    Question Eight:
    Mew = 1/5. Particle A is on a horizontal plane and has mass 1.5kg. Particle B is on a verticle rope and hangs with mass 3kg. Both are connected to a pulley so that the angle between them is 90 degrees. A is to the left of B.
    a) Find Tension
    b)Find magnitude of tension on pulley
    Estimates for grade boundries/UMS?
 
 
 
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