Moments
This lesson covers:
- What a 'moment' is
- The moment equation: 
- Balanced moments in seesaws
A moment is the rotational or turning effect of a force.
The formula a for moment is:



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In the formula:

 is the perpendicular distance between the force and the pivot.
The units for moment are:
Metres (m)
Newtons per metre (N/m)
Newtons (N)
Newton metres (Nm)
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An object is rotated with a force of 5 N at a perpendicular distance of 0.4 m from the pivot.
What moment is generated?
Nm
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A force of 4 N is applied to an object, generating a moment of 20 Nm.
What is the object's perpendicular distance from the pivot?
m
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In a balanced seesaw, the total clockwise moment is ________ the total anti-clockwise moment.
less than
equal to
more than
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 A cow weighs 10,000 N and is sitting on a seesaw 2.4 m from the pivot. A walrus weighs 12,000 N and is sitting on the other side of the seesaw. The seesaw is balanced. |
What is the moment generated by the cow? Nm
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The moment generated by the cow is: Clockwise Anti-clockwise
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As the seesaw is balanced, the clockwise moment generated by the cow will equal the anti-clockwise moment generated by the walrus. Thus, the moment generated by the walrus must also be 24,000 Nm. |
What is the distance of the walrus from the pivot? m
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A lion weighs 6,000 N and is sitting on a seesaw 1.8 m from the pivot.
A group of people are standing on the other side of the seesaw, they weigh a combined total 9,000 N.
The seesaw is balanced. What is the distance of the group of men from the pivot?
m
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What units do we use to measure moments?
Newtons (N)
Newton metres (Nm)
Newtons per metre (N/m)
Metres (m)
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