Questions tagged [moment]
166 questions
18
votes
3 answers
How does a lever arm increase force?
A lever and a fulcrum is able to to multiply the input force to the output force and trade moving distance for increased force. The same happens in automobile transmissions, taking advantage of high motor RPMs.
What exactly is the physical mechanism…
Erik
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16
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4 answers
Dipole Moment: what does it really represent?
Wikipedia gives the most general expression for the $n^{\rm th}$ moment $\mu_n$ of a physical quantity $\Lambda$ as:
$$ \mu_n = \int {\bf x}^n \space \delta({\bf x}) \space \rm d^3 x$$
provided that we know the spacial distribution density…
ric.san
- 1,694
15
votes
2 answers
Do higher-order mass moments have any physical meaning?
The zeroth moment of mass of an object is simply its total mass.
The first moment of mass yields an object's center of gravity (after normalization).
The second moment of mass yields an object's moment of inertia.
Is there an analogous physical…
David Zhang
- 646
14
votes
4 answers
Torque vs Moment
I was wondering, why in Newtonian physics torque is called "torque" while in static mechanics they call it "moment"?
I prefer by far the term "torque", for not only it sounds strong, but also instead of moment, the correct synonym of torque is…
Severo Raz
- 251
12
votes
1 answer
Meaning of the word "Moment"?
This question is more of a question about the origin of a physical term moment used in many contexts.
My question is about the linguistic or historical meaning of the word "moment".
Please don't provide the mathematical equations for the moment of…
alqubaisi
- 141
11
votes
6 answers
What is the role of pillars in bridges?
As I can see in the picture, there are so many pillars which are holding the bridge. This picture gave a question to me that what are these pillars doing below the bridge?? An appripriate answer could be "these are providing support to bridge".
I…
Vidyanshu Mishra
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10
votes
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How can a bowling ball curve in both directions?
There is a popular video on facebook that I just don't understand. A man spins a bowling ball very fast then slightly taps it down the lane. Somehow it does half of a figure eight, curving around two pins. Can anyone explain the physics behind it?…
Seth Kitchen
- 153
9
votes
7 answers
Difference between torque and moment
What is the difference between torque and moment? I would like to see mathematical definitions for both quantities.
I also do not prefer definitions like "It is the tendancy..../It is a measure of ...."
To make my question clearer:
Let…
Amr
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9
votes
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Why does Torque exist?
Specifically, why does force increase with the moment arm? What about making a perpendicular force farther away from the axis of rotation increases it? How does the moment arm cause that?
BoddTaxter
- 2,948
9
votes
4 answers
The momentum of a swinging sword
Suppose you are faced with a zombie, and the only way to kill it and save yourself is to chop its head off with your sword. However, you are very weak from illness, and can only afford to strike once.
Question:
To ensure that you cut in a single…
Deep
- 393
9
votes
4 answers
Are there 'higher order moments' in physics?
This may be a rather noob question but please let me clarify: I'm struggling to understand the use of the word 'moments' w.r.t., probability distributions. It seems after some research and poking around it seems to have been derived from physics…
PhD
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8
votes
3 answers
Are gravitational quadrupole moment, second moment of mass, and moment of inertia the same?
my understanding of moments is that they refer to distributions about an expected value, which allows us to make the multipole expansion. I read that:
the zeroth moment of mass refers to the mass of the body itself, first moment refers to the…
user107224
- 640
8
votes
1 answer
Why is a dipole moment called a dipole moment?
The General Formula for a moment is the following one:
$$
\vec{M} = \vec{r} \times \vec{F}.
$$
However the formula for a dipole moment is this one:
$$
\vec{p} = Q \vec{d}.
$$
How comes this is still called a "moment"? A charge is not the same as a…
GrapherLord
- 83
7
votes
2 answers
First and Second Moment of Mass
I recently came across the definition of the Center of Mass of a system as the point about which the first moment of mass is zero.
Further, it defined Moment of Inertia as the second moment of mass.
My question is, What is this 'moment of mass'?
noir1993
- 2,226
6
votes
4 answers
What is a moment?
As a 8th grader I am still a newbie at science and I have problems understanding the forces that I can not imagine and one of these "forces" is the moment.
We are told that,
$$\text{moment}= Nm$$
but how can a certain force (i.e. $N$) be applied…
Mythical Miner
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