Questions tagged [work]
The product of the force on an object and the displacement the object undergoes along the direction of the force.
3,244 questions
-3 votes
0 answers
33 views
How much power must be supplied by the winch? [closed]
A 1380-kg block of granite is dragged up an incline at a constant speed of 1.34 m/s by a steam winch (Fig. 11-32). The coefficient of kinetic friction between the block and the incline is 0.41. How ...
1 vote
3 answers
223 views
Where is the increased mass reserved based on Einstein's mass-energy equation?
Assume a huge parallel-plate capacitor with plates located at an infinite distance away from each other. If we tend to move a positively charged object ($+q$) with a rest mass of $m$ against the ...
- 2,920
0 votes
2 answers
96 views
How could one show that kinetic friction is a non-conservative force?
The question is not to talk about why kinetic friction is non-conservative, but rather if there is a way that I could show mathematically that the work done by kinetic friction is path-dependent?
- 15
6 votes
1 answer
288 views
Does the electric potential energy of a positively-charged particle vary directly with its distance from a charged particle or surface?
Current high school AP Physics II student here, so apologies if this question comes off as unlearned. I'm trying to learn about electric potential in my class, but I realize I still don't understand ...
- 63
-2 votes
1 answer
98 views
Can gravity make an infinite amount of energy? [closed]
If we use gears, then we put a long metal stick then put a $100\text{ kg}$ metal object on it, assuming there are $200$ gear and each has a ratio of $1:5$, because a larger section of the double gear ...
- 15
0 votes
0 answers
52 views
Why am I getting Work done as negative in bringing a positive charge near another positive charge? [duplicate]
Let us consider a charge $Q>0$ at origin. Let $P(r,0)$ where $r>0$ be on $X$ axis.Consider a point $M(x,0),\:x>r$ from which we have to move a charge $q>0$ towards point $P$. Now I am the ...
- 113
1 vote
2 answers
84 views
Q&A: Potential (Energy) and its Sign: inverse square law, comprehensively compiled [closed]
There have been a lot of questions (and I want to highlight a wonderful answer) on the topic of potential energy and its sign, in both the gravitational case and the electrostatic case, about the ...
- 18.3k
2 votes
2 answers
267 views
Why does Callen not take into account the change in entropy of the reversible work source?
I am reading the second edition of Callen's Thermodynamics and in particular about the maximum work theorem which essentially states that a process which produces work and heat produces maximum work ...
- 1,196
0 votes
7 answers
553 views
How can the work-energy theorem be applied in case of a block impacting a massive spring?
We have a spring with uniformly distributed mass $m$ and stiffness $k$, with free length $x_0$ aligned with the $x$-axis, lying on a friction-less table. A block of mass $M$ is moving towards it along ...
- 47.4k
0 votes
5 answers
171 views
Ambiguity in work-energy theorem for a system
in this question if I have to find max compression in spring then if I consider both block and spring as system and then apply work energy theorem then as I have written above that spring force is ...
-6 votes
3 answers
163 views
Why is it watt second instead of watt per second? [closed]
We say 1 meter per second to express 1 meter covered in 1 second. Why can't we say 1 watt per second when 1 watt is used in 1 sec?
10 votes
10 answers
1k views
What does it mean for work to be done ON a system?
I have been reading different literature on thermodynamics for a course at university, and of course, the idea of work being done ON a system is very central. What is rather seldom explained, perhaps ...
- 1,196
2 votes
1 answer
222 views
Geometric mean used to calculate gravitational work $L_{AB}=U(A)-U(B)$
We know that $$ \mathbf{F}^{G}(r) = -\frac{GMm}{r^2} \, \mathbf{\hat{r}} $$ where $\mathbf{\hat{r}}$ is the unit vector in the radial direction. I want to calculate the work $L_{AB}$ done by this ...
- 2,907
0 votes
3 answers
191 views
Definition of conservative forces [closed]
Can we say that a conservative force is a force whose direction doesn't change with change in direction of the velocity (of the body)? For example the direction of frictional force changes with change ...
- 11
0 votes
5 answers
429 views
What's the philosophical understanding of work, energy, conservative forces? [closed]
I have a particular way of studying physics- I focus on building the philosophical understanding of each idea/concept without using any math/formulae. Once I feel confident enough in my understanding, ...
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