All Questions
Tagged with classical-mechanics work
214
questions
3
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answer
358
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Conservative field vs conservative force
For a conservative field (e.g. electrostatic field) the circulation of the field (along a closed line) is zero.
For a conservative force (e.g. macroscopic elastic force) the work performed on a ...
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3
votes
2
answers
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What is difference between variations of the work and virtual work?
I really want to know whether or not both equations are the same mathematically. I think that they are the same, I just want to be sure.
(Reference: this website.)
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3
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2
answers
613
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Net Work Done When Lifting an Object at a constant speed [duplicate]
I am confused about the amount of work done when lifting an object at a constant speed. If you find the work done by you on the object and the work done by gravity on the object and add them the net ...
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votes
7
answers
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Centripetal Force Acceleration
In uniform circular motion, acceleration is $\frac{v^2}{r}$ and time which it acts $\rightarrow 0$.
So $\Delta v = 0$, but then why/how does direction change, when the acceleration should be producing ...
user23503
2
votes
5
answers
317
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Can a conservative force not conserve mechanical energy because of explicit time dependence?
Let us define a conservative force as being a force whose work is path independent. Then, in particular, a vanishing force is conservative.
If a force acting on a particle can be written from a scalar ...
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2
votes
2
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260
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Mechanical work to required battery power
I have a very practical question where I've calculated the mechanical work needed by a simple mechanical system by solving the line integral $W = \int_C \ F \ dx$. However, since I have a black spot ...
- 333
2
votes
4
answers
292
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How do we get energy to start walking?
The answer seems obvious, it's our energy that gets converted into kinetic energy. But my question is how exactly? Which force is responsible for doing work on us so that we gain kinetic energy? It ...
- 351
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votes
1
answer
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How to prove force is conservative?
How do I prove whether a force perpendicular to the motion is conservative and $\mathbf{F}=\mathbf{F_{0}}\sin(at)$ conservative, where $\mathbf{F_{0}}$ is a constant vector.
I knew that for a force ...
- 494
2
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3
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Why is walking up stairs harder than walking normally?
I must admit, I'm pretty new to studying physics and I know this is a simple concept but I'm having difficulty understanding it. I've tried reading the questions here but I just need a little bit of ...
- 123
2
votes
2
answers
775
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How does the work-energy theorem relate to the first law of thermodynamics?
The work energy theorem states that the net work on a particle is equal to the change in the kinetic energy of the particle:
$$W_{net}=\Delta K $$
My first question is whether this formula (the work-...
- 1,581
2
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1
answer
143
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Example of a single constraint force doing virtual work despite the sum of work done by constraints being zero
When deriving d'Alembert's Principle it must be assumed, that the total virtual work done by constraint forces vanishes.
$$\sum_{j=1}^N\mathbf{C}_j\cdot\delta \mathbf{r}_j=0.$$
In the books I've read, ...
- 72
2
votes
5
answers
924
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Where does the power delivered to car's wheels go?
Okay, so power is work/time. Most cases, when power is provided to something, energy is gained as kinetic energy or lost to friction.
But in a car, the engine puts power ( torque x rpm/5252) to ...
- 379
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1
answer
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How Much Power Is Required to Hover?
Suppose I have a spaceship that weighs 1,000 kilograms. I take it to the surface of the planet with a gravitational acceleration of 10 meters per second-squared. The planet has no atmosphere and I'm ...
- 277
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1
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Why is $t$ considered constant when forming the differential $\mathrm dU(q_l; t)$ for $\mathrm dU= \overline{\mathrm dw}$ to be true?
The definition of work function on the basis of $$U:= U(q_1,q_2,\ldots,q_n)\tag{17.6}$$ is too restricted. We have forces in nature which are derivable from a time-dependent work function $U(q_1,q_2,\...
user36790
2
votes
1
answer
329
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Why does a system have to be holonomic?
So I'm doing some work from Taylor's mechanics book. He says for the problems in the book, we require the system to be holonomic - that is the number of generalized coordinates = number of Deg. of ...
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