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    Correct! 3 marks to you Sir!

    Q: (Follow up to the one answered) As the aircraft moves along the runway for take-off, its acceleration decreases even though the force from the engines is constant. Explain why?

    (2 marks)
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    (Original post by toby_ling)
    Q: (Follow up to the one answered) As the aircraft moves along the runway for take-off, its acceleration decreases even though the force from the engines is constant. Explain why?
    (2 marks)
    the faster an object is moving through a fluid, the greater the resistive forces acting on it. Therefore, with the same driving force, there is a greater frictional force, therefore resultant force is smaller --> decreased rate of acceleration.
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    P2 questions from AQA:

    1.
    a) Why does the plasma of light nuclei in a fusion reactor need to be very hot?
    b) Why would a fusion reactor that needs more energy that it produces not be much use


    2. A student is doing an investigation of the conservation of momentum with a horizontal air track and two gliders.

    a) Explain what is meant by the conservation of momentum
    b) apart from collisions, give another type of event in which conservation of momentum applies


    3. There are two gliders, X and Y
    The mass of X is 0.2kg and its velocity is 1.5m/s to the right
    The mass of Y is 0.3kg and it is stationary
    When glider X colliders with Glider Y they move off together

    Calculate the velocity of the gliders after the collision and give their direction.
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    (Original post by hughey)
    the faster an object is moving through a fluid, the greater the resistive forces acting on it. Therefore, with the same driving force, there is a greater frictional force, therefore resultant force is smaller --> decreased rate of acceleration.
    Correct! Good answer! I would mention that the force was air resistance just to be sure of the full marks, you never know about AQA!
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    (Original post by neomilan)
    P2 questions from AQA:

    1.
    a) Why does the plasma of light nuclei in a fusion reactor need to be very hot?
    b) Why would a fusion reactor that needs more energy that it produces not be much use


    2. A student is doing an investigation of the conservation of momentum with a horizontal air track and two gliders.

    a) Explain what is meant by the conservation of momentum
    b) apart from collisions, give another type of event in which conservation of momentum applies


    3. There are two gliders, X and Y
    The mass of X is 0.2kg and its velocity is 1.5m/s to the right
    The mass of Y is 0.3kg and it is stationary
    When glider X colliders with Glider Y they move off together

    Calculate the velocity of the gliders after the collision and give their direction.
    0.6 m/s?
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    0.3 kg m/s is combined momentum after cllision. To work out velocity for both objects once there is an impact, you calculate 0.3 kgm/s divided by the combined mass which is 0.5kg = 0.6 m/s
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    Hi, I have a question.

    "A white snooker ball of mass 0.1kg moving at 0.5m/s hits an identical, stationary red ball. After the collision, the white ball contines in the same direction at a speed of 0.2 m/s. What is the speed of the red ball after the collision?"

    :shock:

    Any ideas? I think it has something to do with momentum....
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    Total Momentum Before Collision = Total Momentum After Collision

    Let v = velocity of red ball after collision

    (0.1 x 0.5) = (0.1 x 0.2) + (0.1 x v)
    0.05 = 0.02 + 0.1v
    0.1v = 0.03
    v = 0.3

    Velocity of the red ball is 0.3 m/s after the collision (would have added the direction to the question but don't know what it is from the question). Am I right?
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    (0.1 x 0.5) = (0.1 x 0.2) + (0.1 x redVelocity)
    (0.05) = (0.02) + (0.1 x v)
    (0.05 - 0.02) = (0.1 x v)
    (0.03) = (0.1 x v)
    v = (0.03/0.1)
    v = 0.3 m/s

    That's what i got
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    Hi guys
    Sorry if this seems a little irrelevant, but anyway.


    I'm doing Dual Award Science.
    If I got a mid-high A in Biology 2, a C in Chemistry 2 and an A in Physics 2 (hopefully) then would that even out at a B?
    In my ISAs I've got an A.

    :|
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    Definatly a B. An A depending on the actual scores i.e. the C is a high C and the A's are high A's.
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    (Original post by neomilan)
    3. There are two gliders, X and Y
    The mass of X is 0.2kg and its velocity is 1.5m/s to the right
    The mass of Y is 0.3kg and it is stationary
    When glider X colliders with Glider Y they move off together

    Calculate the velocity of the gliders after the collision and give their direction.
    (Original post by ...bored)
    0.3 kg m/s is combined momentum after cllision. To work out velocity for both objects once there is an impact, you calculate 0.3 kgm/s divided by the combined mass which is 0.5kg = 0.6 m/s
    why is 0.3 their combined momentum? i thought you work out the momentum of X = 0.3 and add to momentum of Y = 0.3 which gives us 0.6
    so combined momentum is 0.6 kg m/s
    and so 0.6 = 0.5 x V
    V = 0.6/0.5
    V = 1.2 m/s ????

    I might be wrong, someone check me :confused:
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    mom = 0.2 X 1.5 = 0.3 kgm/s
    0.3 = 0.5 X V
    V= 0.6 m/s

    Im not sure how you are doing it but this is the correct method

    Keep in mind the conservation of momentum says that the TOTAL momentum before the collision is equal to the total monemtum after the collision

    FInd out the momentum before using the formula mom (momentum) = vel (velocity) X weight

    mom = 1.5 (because its moving 1.5m/s to the right) X 0.2 (the weight of the object)
    mom = 0.3

    because of conservation of monemtum says the total momentum before (0.3) is equal to the total momentum afterwards, the total omentum aftefr the collision is 0.3

    so
    0.3 = 0.5 (the weight of the 2 objects added together) X vel
    whioch gives vel as 0.6 m/s

    hope that helped
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    This is a great topic! I've learnt quite a bit.. good luck to everyone with the exam tomorw! I got it too.. :|
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    Circuits are what I'm struggling with most- anyone have an easy way to remember how current, pd etc. works in different types of circuits?
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    I hate circuits!! Not that they are too hard...they're extremely boring...and I can look forward to them next year...
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    Voltage in Series adds up.
    Voltage in parrellel is the same everywhere

    Current in Series is the same everywhere
    Current in Parrelel adds up, is that correct?
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    ^^ yeah thats correct
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    This is how i remember it



    ________| Series | Parralel |
    Voltage | Shared .| Same___|
    Current | Same__| Shared__|



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    Static Electricity ARGHHHHHHHHHHHHHHHHHHH
 
 
 
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