All Questions
Tagged with definition forces
180
questions
112
votes
6
answers
13k
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Are Newton's "laws" of motion laws or definitions of force and mass?
If you consider them as laws, then there must be independent definitions of force and mass but I don't think there's such definitions.
If you consider them as definitions, then why are they still ...
- 3,043
45
votes
3
answers
8k
views
History of interpretation of Newton's first law
Nowadays it seems to be popular among physics educators to present Newton's first law as a definition of inertial frames and/or a statement that such frames exist. This is clearly a modern overlay. ...
user4552
35
votes
4
answers
4k
views
The physical definition of work seems paradoxical [duplicate]
So this is possibly a misunderstanding of the meaning of work, but all the Physics texts, sites, and wiki that I've read don't clear this up for me:
In the simplest case with the simplest statement, ...
- 1,229
34
votes
5
answers
65k
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Why is the potential energy equal to the negative integral of a force?
Why is the potential energy equals to the negative integral of a force? I am really confused with this negative sign. For example, why there is a negative sign in the gravitational potential energy ...
- 736
33
votes
11
answers
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Why does work depend on distance?
So the formula for work is$$
\left[\text{work}\right] ~=~ \left[\text{force}\right] \, \times \, \left[\text{distance}\right]
\,.
$$
I'm trying to get an understanding of how this represents energy.
...
32
votes
15
answers
6k
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What is the fundamental definition of force?
As I pick up more physics I see that the definitions of force commonly provided in books and classrooms are misleading.
"A force is a push or pull." This seems to be a "correct" ...
- 725
20
votes
3
answers
4k
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Conditions for a force to be conservative
Taylor's classical mechanics ,chapter 4, states:
A force is conservative,if and only if it satisfies two conditions:
$\vec{F}$ is a function of only the position. i.e $\vec{F}=\vec{F}(\vec{r})$.
The ...
- 1,295
15
votes
6
answers
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Why is stress defined in the way as it is?
Stress is like pressure and it doesn't matter in which direction the force acts (given it is perpendicular to the surface).
I read in my book that if we have a rope which is being pulled on both ...
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14
votes
9
answers
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Why is momentum defined as mass times velocity?
Why is momentum defined as mass times velocity? I asked this question because everywhere people try to answer this by saying that $F=ma$ and if we integrate it with respect to ${\rm d}t$ we can get $p=...
- 209
13
votes
4
answers
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What does Feynman mean when he says that $F=ma$ is not exact?
Chapter 12-2 in Feynman Lectures Vol. 1 states:
In fact the law, $F=ma$ is not exactly true; if it were a definition we should have to say that it is always true; but it is not ...
First, because ...
- 331
11
votes
4
answers
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Define Pressure at A point. Why is it a Scalar?
I have a final exam tomorrow for fluid mechanics and I was just looking over the practice exam questions. They do not provide solutions. But pretty much I have to define pressure at a point and also ...
- 1,158
11
votes
10
answers
2k
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What distinguished physical and pseudo-forces?
Why are some forces are considered pseudo-forces while some are considered real or physical forces?
The definition of pseudo-forces that I know of is that they exist in noninertial reference frames ...
- 1,235
10
votes
4
answers
2k
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Does the displacement in the definition of work correspond to the displacement of the object or the point of application of the force?
Work is defined as
$$W = \vec{F}\cdot\vec{s}$$
But what what exactly is $\vec{s}$? Is it the displacement of the body on which the force is being applied? Or is it the displacement of the point of ...
- 2,770
9
votes
2
answers
10k
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Why is Newton's third law known as *weak law of action and reaction*?
This link shows the extra requirements for strong law of action and reaction. Why is Newton's third law known as weak law of action and reaction? Is the strong law of action and reaction not Newton's ...
- 2,754
8
votes
5
answers
607
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Why is torque defined as $\vec{r} \times F$?
Here I cannot convince myself myself that it is units because the torque is defined to be in units of Newton meter is a reiteration of the law stated above. Why was it not $r^2 \times F$ or $r^3 \...
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