What is Work done: Definition and 1000 Discussions
In physics, work is the energy transferred to or from an object via the application of force along a displacement. In its simplest form, it is often represented as the product of force and displacement. A force is said to do positive work if (when applied) it has a component in the direction of the displacement of the point of application. A force does negative work if it has a component opposite to the direction of the displacement at the point of application of the force.
For example, when a ball is held above the ground and then dropped, the work done by the gravitational force on the ball as it falls is equal to the weight of the ball (a force) multiplied by the distance to the ground (a displacement). When the force F is constant and the angle between the force and the displacement s is θ, then the work done is given by:
W
=
F
s
cos
θ
{\displaystyle W=Fs\cos {\theta }}
Work is a scalar quantity, so it has only magnitude and no direction. Work transfers energy from one place to another, or one form to another. The SI unit of work is the joule (J), the same unit as for energy.
Homework Statement
The fastball of a famous pitcher in the National League has
been clocked in excess of 95 mph. Calculate the work done
by the pitcher in accelerating the ball to that speed. The
mass of a baseball is 0.145 kg.
mass = 0.145 kg
final velocity (in m/s) = 42.4688 m/s...
Let say we have a horizontal mass-spring system oscillates without friction on a smooth surface.
One side of the spring is attached / fixed to a wall. The other is where the mass is attached to.
Let say we choose our system to be the mass and the spring (negligible mass), so our free body...
capacitor -- Work done to charge it up
If we imagine a capacitor as two conductors held a distance d apart from each other, we can find easily that the total charge and the potential are proportional:
Q = CV
To find the energy stored in a capacitor you can imagine taking a tiny chunk of...
In physics, work is said to be done by a force. In the field of electricity, work is done by an electrical field. In thermodynamics, work is done by a system. This is kind of confusing and makes me wonder, what is actually the thing that does work? Is it the object, the force field or the force...
Homework Statement
http://s9.postimage.org/5iw5rixyl/image.jpg
(sorry doesn't let me embed)
Homework Equations
P1V1=P2V2
and
PV=nRT
I know that Work done by gas from a --> b = (nRT)*Integral(V2/V1)
My question is do i use PV=nRT to find N? and if T is constant (isothermal) what do I plug in...
Homework Statement
(a) How much work is done on the steam when 3.89 mol of water at 100°C boils and becomes 3.89 mol of steam at 100°C at 1.00 atm pressure? (Assume the latent heat of vaporization of water is 2.26 106 J/kg.)
(b) Assume the steam to behave as an ideal gas. Determine the...
Two straight current carrying conductors A and B are lying in a vertical plane as shown.The separation between them is h and mass per unit length of wires is λ.Keeping one wire fixed (say A),Bis raised by small hieght δh.
Q-1 What would be the work done by external agent?
Q-2 Will the work...
As the title alludes to, I am currently reading about work. One sentence has left me very confused, thought: " Only the magnitude of this variable force changes, not its direction,
and the magnitude at any position does not change with time."
Could someone possibly help me understand this?
Homework Statement
Spheres of masses m1 2.53kg and m27.16kg are fixed at a distance 1.56m apart centre to centre.A m3 212 g sphere is positioned 42cm from the 7.16 kg fromcentre of 7.16 kg sphere along the line of centres.How much work must be done by ext agent to move thesphere of 212 g...
Homework Statement
How do you find the work done in charging a capacitor and the work done on a charge in an electric field.
I don't know the formulas.
Homework Statement
3 charges, A,B, and C are located at the vertices of an equilateral triangle. Point P is at the center of the triangle, and is 8 cm from each charge. Charge A is +7 μC. Charge B is +6 μC. Charge C is -10μC. If a 4μC charge is brought from infinite to point P, how much work...
Dear fellows
I have three questions related to the topic “Lifting an object against gravity”.
If we lift an object of mass 5kg we need to apply a little more force than its weight to lift it and suppose we apply 50 N force (gravity is exerting 49 N forces on it) for just a second that...
It must be, right? Obviously, if you're pushing a block by exerting a force F on it over a distance D on the ground, if you are in the frame of you or the block, your distance is 0 so it appears you're doing no work.
I ask this question because I was doing a practice problem that should be...
Homework Statement
I am supposed to determine whether work is being done on or by a closed thermodynamic system from a diagram that's sort of like this, and provide justification for my answer:
My problem is I have no idea how to tell if that system is doing work or if work is being done...
Homework Statement
A parallel-plate capacitor is charged to an electric potential of 100 V by moving 4x10^19 electrons from one plate to the other. How much work was done?
Homework Equations
How much work was done?
The Attempt at a Solution
Work is then simply equals to...
Homework Statement
1. A small plane tows a glider at constant speed and altitude. If the plane does 2.00 x 105 J of work to tow the glider 145 m and the tension in the tow rope is 2560 N, what is the angle between the tow rope and the horizontal?
2. Water skiers often ride to one side of...
hi guys I am swamp with work and have not been able to go through my assignments proper
[b]1. one cube meter of an ideal gas at 600K and 1000Kpa expands to 5 times its initial volume: by mechanically reversible, isothermal process and by a mechanically reversible, adiabatic process...
If work is done on or by a object. Is the force perpendicular to the displacement? For any object that is in motion or able to do work or work is being done on it.
Example:
A ball thrown up in the sky, force applied on the ball is perpendicular to the displacement.(Is this applied on...
Suppose I have an object moving in a free space at initial velocity of v (no friction). Then two forces of equal magnitude but opposite directions are applied on the moving object of which one of them is in the same direction as the moving object. Is there work done by that force?
"A 50 kg crate is being dragged across a floor by a force of 225 N at an angle of 40° from the horizontal. The crate is dragged a distance of 5.0 m and the frictional force is 60 N."
Now from that information i am supposed to find the work done by the applied force on the object.
This is...
Can anyone tell me the relationship between work done and potential difference??
CAN ANYONE TELL ME THE RELATIONSHIP BETWEEN WORK DONE AND POTENTIAL DIFFERENCE??
If more work is being done across a component(for ex due to increased resistance), does the pd across it increase or decrease? I...
hello, I've been searching the forum here, many websites and books and i just don't get it. The potential difference between two points in a circuit is the work done AGAINST the electric field so who's making the work in a circuit? isn't suppose to be the Electric Field? and in a circuit the...
Homework Statement
Ideal gas initially at temperature Ti, Pressure Pi, Volume Vi is compressed reversibly down to half its original volume. Temperature of gas is varied during the compression so that
P = AV is always satisfied [where A is a constant]
Show that the work done on the...
imgur.com/kBTVm
Hi,
I understand that work done in a conservative field when a closed loop is followed is zero.
The answer to this question I am sure is B. How do I explain to my colllegue that it is not zero when he thinks that the speed is constant and there is no friction and the force...
If you apply a force F and compress a spring of spring constant k by x distance what is the work done by us?
I know energy stored is 1/2kx2 but is the work done by us the same?
We are applying a cosntant force F and dispalcement is x so work done by us should be Fx right? And F = kx so work...
Situation 1: completely horizontal circle
Imagine a ball being whirled in a completely horizontal circle.
The only forces acting are tension and weight
Would I be correct in assuming that in this situation NO WORK is done on the ball because the forces are directed (at all times)...
Could someone please prove why the work done by a gas is the area under a PV diagram?
That is, I know that dW=P \text{ }dV, but why is that true physically? I realize that W=f \cdot d \text{ and } F=P \cdot A .Thanks.
Pressure, Volume and Temp Change...WORK done?
n = 9.95 moles of an ideal gas are slowly heated from initial pressure P1 = .922 atm and initial volume V1 = 679 L to final pressure Pf = 1.16 atm and final volume Vf = 1073 L. Find T1, the initial temperature of the gas. If the plot of this...
Homework Statement
Rocket motors make a rocket of mass of 2200kg accelerate at 2.5m/s^2 over a distance of 650m in deep space. What is the work done?
The Attempt at a Solution
F=m*a 2200kg*2.5m/s^2 = 5500N
5500*650= 3575000
When I look at the answer page it tells me the force...
In the line integral of work done by conservative forces, should we care about the direction of force and differential displacement if we choose different coordinate system? The formula of potential energy comes out to be different if we choose different coordinate system.
In a mathematical model, a gas is under a pressure of the form P=e-v2 (v is volume). Find the work (in Joules) done on the gas as its volume decreases from infinity to zero.
dW = PdV
Solution Attempt:
W=∫0∞e-v2dV
http://en.wikipedia.org/wiki/Gaussian_integral
Gaussian...
In a mathematical model, a gas is under a pressure of the form P=e-v2 (v is volume). Find the work (in Joules) done on the gas as its volume decreases from infinity to zero.
If work is displacement times force, lifting a weight up and bringing it down to the same spot would have zero displacement, and thus zero work is done.
However, isn't work a path function? In thermo we learned that heat and work were path functions while quantities such as internal energy and...
Homework Statement
Find the work done by friction force as it slides down an inclined plane in terms of...
m (Mass)
x (Displacement)
μ (Friction Coefficient)
θ (Angle of the inclined plane)
Homework Equations
ƩFnormal = mgcos(θ)
ƩFhorizontal = mgsin(θ)
ƩFfriction = μFnormal -...
a 500 kg crate is on a rough surface inclined at 30°. A constant external force
P = 4000 N is applied horizontally to the crate. The force pushes the crate a distance of 3.0 m up the
incline, in a time interval of 9.2 s, and the velocity changes from ν1 = 1.0 m/s to ν2 = 2.8 m/s. The
work...
Homework Statement
How much work is done to separate an electron from a proton by a distance of 0.1 m?
Homework Equations
Work = F * d
The Attempt at a Solution
I Tried finding the electric force and then plugin it into the Work formula
Therefore (-2.31*10^-26N)(0.1m)?
Work done is defined as F vector. dx vector or F dx cos θ where θ is the angle between F vector and dx vector.
But, there is another common formula-
dU=-F.dx
Here, dU is the potential energy stored in the object on which the force is acting upon. (Am I correct?)
But, the work done on the...
Homework Statement
Homework Equations
The Attempt at a Solution
now I know this has something to do with energy done on electron and KE.
apparently work done on electron is:
W = eV
BUT surely this implies V is constant. as the charge moves, will not V change?
hence it should be
W = 0.5*eV?
The energy stored on a charged capacitor is 0.5*Q*V or 0.5*C*V2
BUT
what is the electrical work done by the supply as it transfers the charge to the capacitor?
I have heard two answers:
W=QV and W=0.5*QV
the first answer implies, i think, that energy is required to move charges against...
Homework Statement
A force acting on a particle moving in XY plane is given by F= 2y i + x^2 j . particle moves from origin to a final position having coordinates (x,y)=(5,5). calculate the work done by force F along
B_____________C
| |
|...
Homework Statement
In the graph attached, why is isothermal graph line higher than adiabatic one??
Homework Equations
The Attempt at a Solution
At first, i had thought that work done in an isothermal process is greater than in an adiabatic process...but for comparison we would...
Homework Statement
I did a lab today in Physics in which we launched ball from a spring loaded cannon directly into a pendulum that captured the ball, held it, and swung upwards with it (representing a totally inelastic collision). One question that confuses me:
> How much work did you do...
This question struck me when i was watching a liquid rise in a capillary tube. I'm curious to know from where the energy gets transferred to the liquid to rise above the surface. Well, one possible explanation that i can think of is air pressure. Though, it can be a possible reason only if the...
Homework Statement
Calculate the work done by a gas as it slowly expands from point A to point B on the pV diagram shown.
Homework Equations
Work=PΔV
The Attempt at a Solution
I calculatate the area under the curve and added both of the areas and I came up with 8*10^11 J and the...
Hello
I'm really confused with this and would appreciate any help.
Homework Statement
a) Show that the work done on a gas during a quasistatic adiabatic compression is given by:
W = \frac{P_f V_f - P_i V_i}{\gamma - 1}
b) Show that the work done by a gas during a quasistatic...
1. As far as the derivation goes, Cp(T02-T01)= Euler work= U2Cx2 in a centrifugal compressor...
where T01 and T02 are the stagnation temperatures...however, in a solved problem in my book, it writes:
Cp(T2-T1)= Euler work= U2Cx2...and therefore uses static temperature instead of stagnation...
1) when a wheel turns there is a forward acting friction but the 'frictional' force that opposes it is rolling resistance right? So when a wheel successfully turns and move does it mean the friction is greater than the rolling resistance?
Then in a car the resisting force will be this rolling...
Homework Statement
if a 10-N force is used to compress a spring with a spring constant of 4.0x10^2N/m, what is the resulting spring compression?
Homework Equations
The Attempt at a Solution
Homework Statement
Calculate a value of R, specific gas constant for air, from the values you have.
Also calculate the work done in the compression process.Homework Equations
Pv = RT
ρair = 1.2 kg/m^3The Attempt at a Solution
Have P,V and T data from an adiabatic compression. I think I need...