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# What terminology do I need to make sure I use for Moments in Paper 2?

1 year ago

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20 Replies

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1614 views

R

Roberta Spinka

Y
Yanwei Liu

The moment of a force measures the turning effect of the force upon a rigid body. It is defined as the product of the magnitude of the force and the perpendicular distance from the axis of rotation. The moment is a vector with unit of Nm

T
Talan Grigg

You must remember the definition of a moment: the Moment, measured in Nm, is equal to the Force applied, F, (N) multiplied by the perpendicular distance, d, from the axis of rotation and the line of action of the force.

Always state the principle of the sum of moments - for an object in equilibrium, the clockwise and anticlockwise moments are equal.

Make sure to to notice how the rod, or beam, ect is described in question - is it massless? If it has mass, is it uniformly distributed? Is it rigid?

Always be looking out for forces not perpendicular to the direction of rotation, you might have to use trigonometry here.

H
Hrishikesh Venkatesh

Sum of anticlockwise moments = sum of clockwise moments.

R
Roland Azuvugu

You should know the principle of moments ( which states that when a beam is in equilibrium under the action of several forces, the sum of all the clockwise moments must be equal to the sum of all the anticlockwise moments about a turning point (pivot) )

A
Abubaker Shabbir

Terminology for Moments. There can be lots terminology that can be used, Im assuming it's pure 2 as your enquiry is in regards to paper 2, so it highly be likely to involve friction. Usual questions can be something to do with finding out if the friction will be sufficient enough to hold an object on a plane for instance once a supporting /external force is removed, in this application I would say working out will be your best friend as well as explaining your steps. When it comes to mechanics always apply the line rule in your working out to ensure its nice and clear for your teacher, examiner and yourself to look back on, to spot any potential mistakes :)

D
Daniel Clark

Heya Robert! When a moments question comes up, ensure you write exactly what you're doing. A good example of this is stating 'taking moments anticlockwise about Point A', and then writing 'taking moments clockwise about Point A'. Later on in the working out, you can also safely write 'Anticlockwise moments = clockwise moments'

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Start the question stating what you are going to do e.g. Take moments about A. Make sure you have a clear diagram and each point is labelled. Then take moments and anti-clockwise and set the two equal to each other if the system is in equilibrium.

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Ashni A Verified Sherpa Tutor ✓

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Moments is the turning effect of a foce about a fixed point called pivot. Moment is a vector quantity. Formula: Moment = Force X Perpendicular distance from the pivot. Unit of Measurement is Nm.

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Moments = force X perpendicular distance from the force to the point you are measuring the moment

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T
Tayyaba Tahreem

Identify major areas of concern in the draft essay during revising

A
Akhil Raghavan

Make sure to always use newton/metres as your units when working out the size of the moment. It is also good to list the formula for moments which is force (newtons) x distance (metres).

You should also know that when in equilibrium, the Anti clockwise moment = clockwise moment.

S
Shaoming Cheng

Hi Roberta,

Moment is newtons (force) multiplied by Meters and it is very important to notify which direction (anticlockwise or clockwise) is the positive direction, otherwise, it is very easy to mix things up!

A

Taking moment about a point, i.e Sum of moment about point O = 0 or the Algebraic sum of clockwise moments about a point is equal to the Algebraic sum of anticlockwise moments about the same point

Moreso, the Algebraic sum of all the vertical forces acting on the body must be equal to zero

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You should make sure you understand that moments have direction. You need to find a direction for the force and also look at the distance in perpendicular direction.

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• the turning effect a force has around a point is a moment,
• A force must act upon an object so that the body would begin to turn,
• Moment = Force X Perpendicular Distance,
• For aan object to be in equilibrium the total moments must be equal,
• The weight of an object operates through its centre of mass

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