A moment is the turning effect of a force about a pivot.

Define centre of gravity .

The centre of gravity (or centre of mass) of an object is the point through which all of its weight can be considered to act.

Where is the centre of gravity located for a symmetrical object of uniform density?

At the object's point of symmetry .

What is the SI unit of a moment?

Newton metres (N m) , although newton centimetres (N cm) may also be used depending on the units given for the distance.

How does the width of an object's base and the height of its centre of gravity affect its stability?

A wider base and a lower centre of gravity make an object more stable, while a narrower base and a higher centre of gravity make it more likely to topple.

A force is applied to an object at an angle to the pivot arm, rather than directly perpendicular to it. Which distance should be used to calculate the moment of this force?

The perpendicular distance from the pivot to the line of action of the force, not the distance to the point where the force is applied.

For a system to be in equilibrium, the sum of clockwise moments about a point must equal the sum of the .......... moments about the same point.

For a system to be in equilibrium, the sum of clockwise moments about a point must equal the sum of the anticlockwise moments about the same point.

Why are door handles placed as far as possible from the hinge?

Placing the handle far from the hinge (the pivot ) increases the perpendicular distance for a given force, producing a greater moment and making the door easier to open.

Under what condition will an object become unstable and topple over?

An object becomes unstable and topples when its centre of gravity is no longer positioned above its base .

True or False? A larger force will always produce a larger moment than a smaller force, regardless of distance from the pivot.

False. A moment depends on both the force and the perpendicular distance from the pivot — a smaller force applied at a greater distance can produce a larger moment than a larger force applied close to the pivot.

True or False? The centre of gravity of every object is located at its physical centre.

False. This is only true for symmetrical objects of uniform density — for irregular or non-uniform objects, the centre of gravity is not necessarily at the geometric centre.

International A Level (IAL)PhysicsEdexcelFlashcards1. Mechanics & MaterialsMoments

Moments (Edexcel International A Level (IAL) Physics): Flashcards

Exam code: YPH11

1/13

0Still learning

Know0

FrontMoments
Define moment.

Was this flashcard helpful?

Cards in this collection (13)

Define moment.
A moment is the turning effect of a force about a pivot.
Define centre of gravity.
The centre of gravity (or centre of mass) of an object is the point through which all of its weight can be considered to act.
What equation is used to calculate the moment of a force?
$Moment = F \times d$
where F is the force in N and d is the perpendicular distance from the pivot in m.
Where is the centre of gravity located for a symmetrical object of uniform density?
At the object's point of symmetry.
What is the SI unit of a moment?
Newton metres (N m), although newton centimetres (N cm) may also be used depending on the units given for the distance.
How does the width of an object's base and the height of its centre of gravity affect its stability?
A wider base and a lower centre of gravity make an object more stable, while a narrower base and a higher centre of gravity make it more likely to topple.
A force is applied to an object at an angle to the pivot arm, rather than directly perpendicular to it.
Which distance should be used to calculate the moment of this force?
The perpendicular distance from the pivot to the line of action of the force, not the distance to the point where the force is applied.
For a system to be in equilibrium, the sum of clockwise moments about a point must equal the sum of the .......... moments about the same point.
For a system to be in equilibrium, the sum of clockwise moments about a point must equal the sum of the anticlockwise moments about the same point.
Why are door handles placed as far as possible from the hinge?
Placing the handle far from the hinge (the pivot) increases the perpendicular distance for a given force, producing a greater moment and making the door easier to open.
Under what condition will an object become unstable and topple over?
An object becomes unstable and topples when its centre of gravity is no longer positioned above its base.
True or False?
A larger force will always produce a larger moment than a smaller force, regardless of distance from the pivot.
False.
A moment depends on both the force and the perpendicular distance from the pivot — a smaller force applied at a greater distance can produce a larger moment than a larger force applied close to the pivot.
In a balanced system, one force ( $F_{2}$ ) produces a clockwise moment, while two other forces ( $F_{1}$ ) and ( $F_{3}$ ) each produce anticlockwise moments about the same pivot.
How are these moments related when the system is in equilibrium?
$F_{2} \times d_{2} = (F_{1} \times d_{1}) + (F_{3} \times d_{3})$
True or False?
The centre of gravity of every object is located at its physical centre.
False.
This is only true for symmetrical objects of uniform density — for irregular or non-uniform objects, the centre of gravity is not necessarily at the geometric centre.

Sign up to unlock flashcards

By signing up you agree to our Terms and Privacy Policy

Previous:Forces & MomentumNext:Work, Energy & Power