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    Module 11 Moments

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    Punitha Pancha
    1) Moments are turning effects caused by forces and depend on the distance of the force from the pivot. The bigger the force or the further it is from the pivot, the bigger the moment. 2) To calculate the net moment, the individual clockwise and anticlockwise moments must be added or subtracted. 3) Simple machines like seesaws and levers trade off force and distance such that applying a small force over a long distance can move a larger load a shorter distance.

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    Module 11 Moments

    Uploaded by

    Punitha Pancha
    66 views4 pages
    1) Moments are turning effects caused by forces and depend on the distance of the force from the pivot. The bigger the force or the further it is from the pivot, the bigger the moment. 2) To calculate the net moment, the individual clockwise and anticlockwise moments must be added or subtracted. 3) Simple machines like seesaws and levers trade off force and distance such that applying a small force over a long distance can move a larger load a shorter distance.

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    Year 8 Moment

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    1) Moments are turning effects caused by forces and depend on the distance of the force from the pivot. The bigger the force or the further it is from the pivot, the bigger the moment. 2) To calculate the net moment, the individual clockwise and anticlockwise moments must be added or subtracted. 3) Simple machines like seesaws and levers trade off force and distance such that applying a small force over a long distance can move a larger load a shorter distance.

    Copyright:

    © All Rights Reserved
    Download as DOCX, PDF, TXT or read online from Scribd
    Download as docx, pdf, or txt
    66 views4 pages

    Module 11 Moments

    Uploaded by

    Punitha Pancha
    1) Moments are turning effects caused by forces and depend on the distance of the force from the pivot. The bigger the force or the further it is from the pivot, the bigger the moment. 2) To calculate the net moment, the individual clockwise and anticlockwise moments must be added or subtracted. 3) Simple machines like seesaws and levers trade off force and distance such that applying a small force over a long distance can move a larger load a shorter distance.

    Copyright:

    © All Rights Reserved
    Download as DOCX, PDF, TXT or read online from Scribd
    Download as docx, pdf, or txt
    of 4

    Fun with Science @Terasek

    Module 11
    Moments
    Moments make things turn or rotate. A moment is a turning effect of a force.

    Forces can make objects turn if there is a pivot.

    They are caused by forces but are not forces themselves. Like forces, moments have a
    direction. We say they are either clockwise or anti-clockwise, to show which way they will
    make something turn.

    The bigger the force causing the turning effect the bigger the moment will be.

    The further the force is from the pivot the bigger the moment will be.

    The size of a moment can be calculated using:

    Moment = Force x Distance

     Force is measured in newtons, N.

     Distance is measured in either m or cm.

     If the distance is in m then the moment will be measured in Nm.

     If the distance is in cm then the moment will be measured in Ncm.

    (Note: The force needs to be at right angles to the lever or rotating object.)

    In many situations there is more than one moment acting. To find the net or resultant
    moment the moments have to be added or subtracted, depending on their direction. Here is
    a worked example:

    1
    Fun with Science @Terasek

    Moment due to A = 20 x 2 = 40 Nm anti-clockwise

    Moment due to B = 10 x 1 = 10 Nm anti-clockwise

    Moment due to C = 20 x 3 = 60 Nm clockwise

    The total anticlockwise moment is 40 +10 = 50 Nm.

    The total clockwise moment is 60 Nm.

    So the resultant moment is 60 Nm - 50 Nm = 10 Nm clockwise.

    Using moments
     A see-saw will balance if the moments on each side of the pivot are equal. This is why
    you might have to adjust your position on a see-saw if you are a different weight from
    the person on the other end.

     If a nut is difficult to undo with a short spanner, a longer spanner will help. This is
    because there will be a bigger moment on the nut, when the same force is applied
    further from the pivot.

     Using the same principle, you can increase the moment applied by a lever or a
    crowbar, and this can help you move heavy objects more easily.

    2
    Fun with Science @Terasek

    Simple machines

    A see-saw is an example of a simple machine. A force is exerted in one place, causing


    movement and a force at another place in the see-saw.

    A balanced beam where the pivot is not in the middle

    A weight of 10N is 2m from the pivot. It has a moment of 10 x 2 = 20Nm. Another weight
    weighs 20N and is 1m from the pivot. The moment is 20 x 1 = 20Nm, so the two weights are
    balanced.

    An effort of 10 N on the left is able to balance a load of 20 N on the right. This would be useful
    if you were trying to lift a heavy load on the right and you pushed down on the left.

    Simple machines give a bigger force but with a smaller movement

    Example 1: Wheelbarrows

    Gardeners and builders use wheelbarrows to carry loads from place to place. The
    wheelbarrow is a simple machine with the load near the pivot (the wheel) and the effort on
    the handles far from the pivot. When you lift the wheelbarrow, the handles move through a
    bigger distance than the load does.

    3
    Fun with Science @Terasek

    Example 2: Forceps

    You may have used a pair of forceps to pick up a small object in the lab. In this case, your
    fingers provide the effort force, and this is nearer to the pivot than the load (the object you
    are picking up):

     some simple machines give a smaller force but with a bigger movement.

    This is the opposite to the see-saw and wheelbarrow, but again if you multiply the force by
    the distance travelled, you get the same value for the effort and for the load.

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