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Help pulleys question a- level m1 Watch

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    2 particles A and B have masses 2m and 3m respectively. The particles are attached to the ends of a light inextensible string. Particle A is held at rest on a smooth horizontal table. Particle B hangs at rest vertically below the pulley with the string taut. Particle A is released from rest. Assuming that A has not reached the pulley, find
    a) the acceleration of B
    b)the tension in the string
    c) the magnitude and direction of the force exerted on the pulley by the string
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    (Original post by thefatone)
    2 particles A and B have masses 2m and 3m respectively. The particles are attached to the ends of a light inextensible string. Particle A is held at rest on a smooth horizontal table. Particle B hangs at rest vertically below the pulley with the string taut. Particle A is released from rest. Assuming that A has not reached the pulley, find
    a) the acceleration of B
    b)the tension in the string
    c) the magnitude and direction of the force exerted on the pulley by the string
    Here is a diagram (practice drawing these)

    For a) create simult equations and solve

    b) use the equations with the info you found from a)

    c) harder to explain, look at the top right of the diagram, you know T so make a right angled triangle and find "F"

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    (Original post by DylanJ42)
    Here is a diagram (practice drawing these)

    For a) create simult equations and solve

    b) use the equations with the info your found from a)

    c) harder to explain, look at the top right of the diagram, you know T so make a right angled triangle and find "F"

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    so tension is the same with arrows going away and towards the pulley?
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    (Original post by thefatone)
    so tension is the same with arrows going away and towards the pulley?
    yes there's only one string so tension is the same at both points
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    (Original post by thefatone)
    so tension is the same with arrows going away and towards the pulley?
    btw in future post questions and the maths forum here; http://www.thestudentroom.co.uk/forumdisplay.php?f=38

    There's more chance of it being seen that way

    best of luck with maths this year and tag me if you need anymore help (and hopefully I can help)
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    (Original post by DylanJ42)
    yes there's only one string so tension is the same at both points
    so can i assume the angle will be 45 degrees since F will cut the right angle directly in half? if so then after that can i use a^2+b^2=c^2?
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    (Original post by DylanJ42)
    btw in future post questions and the maths forum here; http://www.thestudentroom.co.uk/forumdisplay.php?f=38

    There's more chance of it being seen that way

    best of luck with maths this year and tag me if you need anymore help (and hopefully I can help)
    ah ok
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    (Original post by thefatone)
    so can i assume the angle will be 45 degrees since F will cut the right angle directly in half? if so then after that can i use a^2+b^2=c^2?
    perfect the questions on inclined planes wont be 45o though, are you edexcel M1?
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    (Original post by DylanJ42)
    perfect the questions on inclined planes wont be 45o though, are you edexcel M1?
    yes however if you do the question and resolve etc i have managed to get a tension of 12mg/5, not sure if that's right or wrong :/
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    (Original post by DylanJ42)
    Here is a diagram (practice drawing these)

    For a) create simult equations and solve

    b) use the equations with the info you found from a)

    c) harder to explain, look at the top right of the diagram, you know T so make a right angled triangle and find "F"

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    i got 12root2mg/5 as the size of the force can you possibly check if it's right?
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    (Original post by thefatone)
    yes however if you do the question and resolve etc i have managed to get a tension of 12mg/5, not sure if that's right or wrong :/
    Sorry i a had to go fordinner

    i got 6mg/5 for the tension, post your workings if possible?


    Also Exercise 3F question 9 part c, have a look at it
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    (Original post by thefatone)
    i got 12root2mg/5 as the size of the force can you possibly check if it's right?
    my answer was half of that, but only because we got different tensions, your method is correct (and maybe your answer is correct too, I could have made a mistake)

    I will post my workings (considering you have done the question and you can compare if you like)
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    (Original post by thefatone)
    2 particles A and B have masses 2m and 3m respectively. The particles are attached to the ends of a light inextensible string. Particle A is held at rest on a smooth horizontal table. Particle B hangs at rest vertically below the pulley with the string taut. Particle A is released from rest. Assuming that A has not reached the pulley, find
    a) the acceleration of B
    b)the tension in the string
    c) the magnitude and direction of the force exerted on the pulley by the string
    http://www.thestudentroom.co.uk/forumdisplay.php?f=38
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    (Original post by thefatone)
    i got 12root2mg/5 as the size of the force can you possibly check if it's right?
    Here are my workings

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    The OP has already been told this ...
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    (Original post by DylanJ42)
    Here are my workings

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    (Original post by Muttley79)
    The OP has already been told this ...
    i was gonna say xD
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    (Original post by thefatone)
    horizontally you have written/wrote (:dontknow:) T - 2mg = 2ma

    but its a smooth table so there is no friction
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    (Original post by DylanJ42)
    horizontally you have written/wrote (:dontknow:) T - 2mg = 2ma

    but its a smooth table so there is no friction
    good point well looks like that'll have to change
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    (Original post by thefatone)
    good point well looks like that'll have to change
    other than that youre doing the questions perfectly

    you would still get all the method marks i would assume
 
 
 
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