# Physics P3 2.1 Moments.

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What is the moment of a force?
A measure of the turning effect of the force on an object.
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What equation is used to determine the size of the moment?
M = F x d.
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How can the moment of a force (F) be increased?
To increase the moment of a force (F), increase F or increase d. Meaning increase either the force or the distance to the pivot.
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What is the turning effect of a force called?
Its moment.
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In the equation for the size of the moment, what is M?
The moment of the force in newton-metres (Nm).
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In the equation for the size of the moment, what is F?
The force in newtons (N).
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In the equation for the size of the moment, what is d?
The perpendicular distance from the line of action of the force to the pivot in metres (m).
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Why is it easier to undo a wheel-nut by pushing on the end of a long spanner than a short one?
Because the long spanner increases the distance between the line of action of the force and the pivot.
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Why do we use a lever to make a job easier?
When using a lever, the force we are trying to move is called the load and the force applied to the lever is the effort. A lever acts as a force multiplier, so the effort we apply can be much less than the load.
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A door opens when you apply a force of 20N at right angles to it, 0.6m from the hinge. What is the moment of the force about the hinge?
12 Nm.
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What force would be needed to open the door if it were applied 0.3m from the hinge?
40 N.
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**IN EXAMS, MOMENT MAY BE APPLIED TO LOTS OF DIFFERENT SITUATIONS BUT THE IDEA IS ALWAYS THE SAME: FOR ANY PARTICULAR FORCE MAKE THE DISTANCE TO THE PIVOT BIGGER TO MAKE THE MOMENT BIGGER**
**EXAMPLES OF SITUATIONS THAT MAY BE USED INCLUDE: OPENING A DOOR OR A CAN OF PAINT, MOVING SOMETHING HEAVY IN A WHEELBARROW, USING A CROWBAR OR A SPANNER**
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**THE MOMENT EQUATION USES THE TERM 'PERPENDICULAR DISTANCE'' WHICH MEANS THE SHORTEST DISTANCE FROM THE LINE THAT THE FORCE ACTS ALONG**
**LOOK UP DIAGRAMS ETC**
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## Other cards in this set

### Card 2

#### Front

What equation is used to determine the size of the moment?

M = F x d.

### Card 3

#### Front

How can the moment of a force (F) be increased?

### Card 4

#### Front

What is the turning effect of a force called?

### Card 5

#### Front

In the equation for the size of the moment, what is M?