Questions tagged [work]

The product of the force on an object and the displacement the object undergoes along the direction of the force.

Filter by
Sorted by
Tagged with
-1
votes
1answer
49 views

What minimum force would you need to apply in order to do work against gravity without accelerating an object? [closed]

In this example, the object is placed on a frictionless surface. After letting go, the object travels back and forth on a U-shaped tack. Without a mass or angle to the incline, how am I supposed to ...
0
votes
0answers
47 views

Work, power and energy in the case of chain [closed]

Please read my question carefully it is not homework question.i did my own work here I am jee advanced aspirant and i have no teacher only Google is my teacher so please don't flag my question as ...
-1
votes
0answers
42 views

Work power and energy in the case of chain [closed]

Please check my work. And my solution here. But my answer does not match with the actual answer. Where I am wrong here?
0
votes
1answer
23 views

Work done on a charge inside a homogeneous electric field and changes in Energy of the system

How to understand the concept of work using the following example: a positively charged particle (with charge $Q$) is placed in between a charged in a homogeneous electric field between the capacitor ...
1
vote
1answer
45 views

Does work done in a capacitor in moving a charge or increasing potential difference always twice the potential energy stored?

On doing calculations like this: Work done in moving a charge across a potential difference = $(CV)V$ = $CV^2$ Potential energy increased = $(1/2)CV^2$ From this work done is twice the potential ...
0
votes
5answers
108 views

Why do we multiply $\cos θ$ in the formula for work?

I know that the formula for work, $W = FS\cos\theta$, where $F$ is the applied force, $S$ is the displacement of the object and $\theta$ is the angle between the applied force and the displacement of ...
5
votes
4answers
514 views

Terminal Velocity and Work

I don't know much yet about energy and work, as I've only had one lesson on it so far. However, our teacher told us that zero work is confusing and that we wouldn't need to know about it (with the ...
0
votes
2answers
36 views

Different work needed for same momentum change in diff ref frames

The amount of work done by a force on an object at rest can be expressed as $$\frac{1}{2}m{v_0}^2$$ Where $v$ is the final velocity of the object as measured by a reference frame A Frame B is moving ...
2
votes
1answer
41 views

Is heat transfer really just work at the microscopic scale? [duplicate]

I am having trouble understanding why a division is made between heat and work. The units for energy is $\text{kg} \, \text{m}^2 \, \text{s}^{-2}$. The only way to obtain this unit is if you exert a ...
0
votes
2answers
27 views

Hyperelastic solids: why cannot the work in a closed process be negative?

While introducing the theory of hyperelastic solids, our professor gave the following example. "Suppose to have a rubber which is undeformed. Then stretch it, and then release it. The final ...
-2
votes
1answer
31 views

total work done [closed]

Let $\mathcal{F}$ be a unit force vector parallel to $(-1,0,1)$ in 3 space. what is the work done by $\mathcal{F}$ on a particle moving along the path given via $(t,t^2,t^3)$. So I know work is just $\...
0
votes
1answer
29 views

Negative Sign in Potential Energy Expression [duplicate]

The potential energy can be mathematically expressed as: $$U=-\int \vec F \cdot d\vec x$$ I do understand the negative sign is basically to adjust in the relation $$K_1+U_1=K_2+U_2$$ What is the ...
4
votes
1answer
60 views

Stair machine Vs stairs. which is harder?

I had a big argument at the pub about the stair machine being easier than actual stairs, and all the people there disagreed, saying that the only difference is air resistance? Are they kidding? My ...
0
votes
1answer
17 views

Finding the electric potential energy when you know the joules and the charge

What equation do you need if you know both the amount of joules required for the work and the charge, to find the distance the charge has travelled and the electric potential energy at the point the ...
0
votes
1answer
32 views

Trying to understand work done in $P$-$T$ diagram [closed]

I am having a hard time understanding the method to find the work done from a $P$-$T$ diagram. The only given information is that $PT^2 = constant$, and I managed to find that $1.414T_b=T_ a$. The ...
0
votes
2answers
32 views

Is the value of the work done by the forces acting on a rigid body frame dependent?

I was going through the definition of "Work of Forces Acting on a Rigid Body" in Wikipedia . Here they have mentioned that work done can be calculated by taking any reference point on the ...
0
votes
1answer
75 views

Is the work done by magnetic field always zero?

In this case the current is flowing in forward direction due to which the force due to magnetic field acts towards the right and the rod moves towards right. Here in this case, I say force causing ...
1
vote
1answer
23 views

Work done to pull half of the rope up

Let's say we want to pull a uniform ( density $\rho$ ) rope of length $a$ up so that it hangs in equilibrium on a nail. This means $a/2$ is hanging on the left and $a/2$ on the right. Let the ...
0
votes
3answers
71 views

Work contradiction?

If work done equals change in kinetic energy and change in gravitational potential energy, is any work done if we move a standing object and at end point its speed is 0 km/h and height remains same? ...
0
votes
2answers
59 views

Why is the curl of an electric field zero?

I'm asking this question only to make sure that my understanding is correct. I know that that curl of an electric field produced by a stationary charge is zero and I also know that that work done in ...
0
votes
1answer
16 views

Is any work done when we force is being applied on any point but only the point of application moves but body does not

In most of the cases when we apply force to any rigid body on any point the body itself starts moving but what about the elastic sort of body ,if I apply any force and only that particular point moves ...
0
votes
1answer
31 views

Work done by the weight when an object moves down

From University Physics with Modern Physics by Young and Freedman, they say: We want to find the work done by the weight when the object moves downwards from a height $y_1$ above the origin to a ...
0
votes
1answer
37 views

Work done by particle [closed]

Sorry if this is a dumb question but: when an electron moves against its natural course of motion in a uniform electric field, i.e. from positive to negative, why is the work done on the electric ...
2
votes
2answers
39 views

$∆H$ when non-expansion work is done

I have learnt that at constant pressure, enthalpy change $∆H=q$ provided no non-expansion work is done. Why is this the case? What will be relationship of $∆H$ with $q$ if non-expansion work is done? ...
11
votes
2answers
3k views

Why is a push up harder to achieve on a mattress?

Why is doing a push up harder on a spring platform, such as a mattress? It might be more to do with lateral movement and stability, its not that you do more work on the vertical movements but rather ...
1
vote
1answer
53 views

Why would a rock thrown upwards, a rock thrown sideways and a rock thrown downwards have the same final speed? [closed]

This is the full question: A girl throws a stone from a bridge. Consider the following ways she might throw the stone. The speed of the stone as it leaves her hand is the same in each case. Case A: ...
11
votes
7answers
2k views

Is no work done when an object doesn't move, or does the work just cancel out?

Let's say I push a block 5 meters with a force of 10 newtons. It can then be said that I did 50 joules of work on the block, since $$W = F*d = 10 * 5$$ However, when I push on the same block which is ...
0
votes
1answer
26 views

Does this vector need to be fixed for the kinetic energy to be constant?

I was solving the following homework problem: A force $\vec{F} = \vec{k} \times \vec{v}$ is applied to a particle of mass $m$. Here $\vec{k}$ is a fixed vector and $\vec{v}$ is the velocity of the ...
0
votes
1answer
18 views

Is it possible for density in pounds per cubic foot, times a volume, to equal a force in pounds?

In the Calculus book "Calculus: Early Transcendentals" by Edwards and Penney, 7th Edition, there is a chapter on Force and Work. In particular, there is a section explaining how to calculate ...
0
votes
2answers
47 views

Work done to bring a mass from an infinite distance away

In the notes I received from high school teacher, it says: How much work is done by the gravitational field of the planet in bringing a satellite from an infinite distance to a position $r$ away? In ...
4
votes
2answers
115 views

Find relation between displacement and time

“A body is moving unidirectionally under the influence of a source of constant power. Find the relationship between displacement $s$ and time $t$.” I proved it using dimensional homogeneity. Power ...
1
vote
1answer
59 views

Work done when jumping

When I jump in the air I have a sudden increase in kinetic energy, this energy must have come from the work done due normal force on the system (me). My question is since the work done is (force)$\...
2
votes
2answers
49 views

Does a magnet lose mass if it’s doing work?

If a standard refrigerator magnet is used to hold up a piece of paper is it doing “work”? If so it would seem to me that energy would be required for that work and then by extension energy would be ...
0
votes
3answers
178 views

Work from a perpendicular force?

I am deeply concerned about a problem I have in past time even not noticed and slid past it without paying any attention, accepting what books write without the slightest idea that this can be a ...
0
votes
3answers
43 views

Can internal forces do work onto object(s) in a system? [duplicate]

I know that internal forces can't do work on a system but can it do work on the bodies in a system? For example, for a ball-earth system, even though gravitational force is internal, it still did work ...
0
votes
1answer
28 views

What is the distinction between work done by torque and force about an axis other than centre of mass?

Suppose a point particle is undergoing circular motion about a fixed point such that a tangential force is accelerating its speed continuously. Now I believe that I can calculate the work done on this ...
0
votes
1answer
33 views

Why is the Work Done indeterministic when we know $∆V=0$?

Given: In a process on a closed system in closed container, the initial pressure and volume are equal to the final pressure and volume. Comment about the Net Work Done by the System, Net Heat given to ...
1
vote
2answers
46 views

Implications of Defining Work as Change in Mechanical Energy

Would it be possible to form a theory of physics centered around the definition of work as the change in mechanical energy of an object/system, rather than the change in kinetic energy? What are some ...
0
votes
0answers
13 views

Can one prove the conservation of all forms of energy from Newton's laws? [duplicate]

I've learnt using the Work-Energy Theorem one can define potential energy and prove the conservation of mechanical energy. However, this only works for conservative forces while some forces in nature ...
0
votes
1answer
68 views

Is the definition of Work done by Torque a general result?

I was going through this post. In the post the person who asked the question mentioned a statement: "Lastly, I am emphasizing that I'm am NOT saying that torque is incorrect, only that the work ...
17
votes
12answers
3k views

Definition of a joule

I'm not getting the definition of a joule. From the definitions I've read if I apply one newton of force to any object, now matter how heavy/ how much mass it has, over one metre in a single direction ...
1
vote
3answers
64 views

Is the $d$ in $W=F*d$ displacement or distance?

My textbooks say that work=force times displacement but when I was considering conservative and non-conservative forces I got a bit confused. I know that the work done by non-conservative forces onto ...
4
votes
1answer
42 views

What would a force position chart look like applied in real life?

In the chart above, you can see the force (N) on the y axis and the horizontal position (m) on the x axis. How would you visualize this in your head? I'm trying to imagine the movement of a 1 kg box, ...
1
vote
2answers
48 views

Finding frictional force of an object on a slope [closed]

Below is a question I'm trying to solve but I can't seem to get the same answer as what the solution is showing me. Is the solution wrong or is there a mistake in the way of how I think? Question: A ...
1
vote
1answer
67 views

Finding power using work as $Fd$ or as change in energy [closed]

This is a question I had been given a few years ago and I have found two different answers depending on how I find work. If I use $W=Fd$ vs $W=E_f-E_i$, I get two separate answers. I must be missing ...
-1
votes
3answers
87 views

Avoiding a confusion with dot product

Some days ago I have asked a question about a formula for power, many generous people have answered my question and clarify for me that the correct formula of work is $$\mathrm{d}W= \mathbf{F}\cdot \...
1
vote
1answer
28 views

Work done for conservative forces is path independent Proof

So I’m looking at the proof for work that is path independent. There is a line were the integral Partial derivative V dr from r1 to r2 becomes Partial derivative V r’ dt from t1 to t2 I’m a bit ...
-1
votes
1answer
72 views

Does force perpendicular to velocity change its magnitude?

Of course there is the definition of work as a scalar product of $\vec F$ (force) and $\mathrm{d}\vec r$ (displacement). That would mean that if the force is perpendicular to the velocity of an object,...
2
votes
2answers
49 views

Does the $Vdp$ term in thermodynamics always imply some kind of work?

I found an answer here: What is $v \, dp$ work and when do I use it? It says that $V\,dP$ term is isentropic shaft work. Let us consider an adiabatic piston gas system which has some sand mass on top ...
1
vote
1answer
29 views

Conceptual question about rotational and translational kinectic energy

My real life problem is to calculate initial translational and angular velocities of a vehicle in a loss of control to a stop (the vehicle will translate and rotate about it's center of mass.) Initial ...

1
2 3 4 5
46