Why doesn't a hydraulic lever violate conservation of energy?
$begingroup$
Suppose I apply some force on one side of Hydraulic lift where area is less, and the fluid in the lift raises some heavier object on the other side where area is more, Now work done is $Forcetimes displacement$ and displacement on both side is same (incompressible liquid) but force on one side is less, so we get more energy on other side. Then why doesn't the law of Conservation of energy fail here.
newtonian-mechanics fluid-dynamics pressure energy-conservation
$endgroup$
add a comment |
$begingroup$
Suppose I apply some force on one side of Hydraulic lift where area is less, and the fluid in the lift raises some heavier object on the other side where area is more, Now work done is $Forcetimes displacement$ and displacement on both side is same (incompressible liquid) but force on one side is less, so we get more energy on other side. Then why doesn't the law of Conservation of energy fail here.
newtonian-mechanics fluid-dynamics pressure energy-conservation
$endgroup$
12
$begingroup$
Your statement “displacement on both sides is same” is incorrect.
$endgroup$
– Farcher
7 hours ago
1
$begingroup$
do you think the levers also violate energy conservation?
$endgroup$
– user8718165
7 hours ago
2
$begingroup$
displacement means "volume", right?
$endgroup$
– JEB
5 hours ago
2
$begingroup$
@JEB hits the point. Displacement here means a distance moved and not the volume displaced.
$endgroup$
– JimmyB
5 hours ago
add a comment |
$begingroup$
Suppose I apply some force on one side of Hydraulic lift where area is less, and the fluid in the lift raises some heavier object on the other side where area is more, Now work done is $Forcetimes displacement$ and displacement on both side is same (incompressible liquid) but force on one side is less, so we get more energy on other side. Then why doesn't the law of Conservation of energy fail here.
newtonian-mechanics fluid-dynamics pressure energy-conservation
$endgroup$
Suppose I apply some force on one side of Hydraulic lift where area is less, and the fluid in the lift raises some heavier object on the other side where area is more, Now work done is $Forcetimes displacement$ and displacement on both side is same (incompressible liquid) but force on one side is less, so we get more energy on other side. Then why doesn't the law of Conservation of energy fail here.
newtonian-mechanics fluid-dynamics pressure energy-conservation
newtonian-mechanics fluid-dynamics pressure energy-conservation
edited 2 hours ago
knzhou
47k11127226
47k11127226
asked 7 hours ago
Sawan KumawatSawan Kumawat
334
334
12
$begingroup$
Your statement “displacement on both sides is same” is incorrect.
$endgroup$
– Farcher
7 hours ago
1
$begingroup$
do you think the levers also violate energy conservation?
$endgroup$
– user8718165
7 hours ago
2
$begingroup$
displacement means "volume", right?
$endgroup$
– JEB
5 hours ago
2
$begingroup$
@JEB hits the point. Displacement here means a distance moved and not the volume displaced.
$endgroup$
– JimmyB
5 hours ago
add a comment |
12
$begingroup$
Your statement “displacement on both sides is same” is incorrect.
$endgroup$
– Farcher
7 hours ago
1
$begingroup$
do you think the levers also violate energy conservation?
$endgroup$
– user8718165
7 hours ago
2
$begingroup$
displacement means "volume", right?
$endgroup$
– JEB
5 hours ago
2
$begingroup$
@JEB hits the point. Displacement here means a distance moved and not the volume displaced.
$endgroup$
– JimmyB
5 hours ago
12
12
$begingroup$
Your statement “displacement on both sides is same” is incorrect.
$endgroup$
– Farcher
7 hours ago
$begingroup$
Your statement “displacement on both sides is same” is incorrect.
$endgroup$
– Farcher
7 hours ago
1
1
$begingroup$
do you think the levers also violate energy conservation?
$endgroup$
– user8718165
7 hours ago
$begingroup$
do you think the levers also violate energy conservation?
$endgroup$
– user8718165
7 hours ago
2
2
$begingroup$
displacement means "volume", right?
$endgroup$
– JEB
5 hours ago
$begingroup$
displacement means "volume", right?
$endgroup$
– JEB
5 hours ago
2
2
$begingroup$
@JEB hits the point. Displacement here means a distance moved and not the volume displaced.
$endgroup$
– JimmyB
5 hours ago
$begingroup$
@JEB hits the point. Displacement here means a distance moved and not the volume displaced.
$endgroup$
– JimmyB
5 hours ago
add a comment |
2 Answers
2
active
oldest
votes
$begingroup$

Displacement in both sides is not same. If on one side of lift the area is $A_1$, and on other side it is $A_2$, and we apply a force $F_1$ on one side to distance $d_1$ then volume decreased in one side is $=A_1 times d_1$
Equal amount of volume will raise in the other side.
So $$A_1 times d_1=A_2 times d_2$$
$A_1 not= A_2$, so $d_1 not=d_2$.
Actually, we need to apply the little force $F_1$ for a greater distance $d_1$.
New contributor
Broly is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
$endgroup$
add a comment |
$begingroup$
The displacement produced is not the same. That is why, energy is conserved.
When you apply force on one side of the opening (with smaller $A$, i.e. $A_1$), the displacement in the piston that does the work on the water is say, $x$. The displacement on the other side of the lift with $A_2$ where $A_2>A_1$, has a displacement smaller than $x$, which we'll call $y$.
What happens here is that the water absorbs energy from the piston and sends it straight to the lift on the other end with area $A_2$. The volume of water remains the same. But the displacements need not be the same.
Consider the work done $W=PDelta V$ where $Delta V$ is the change in volume. Since the first and the second openings are subjected to the same pressure (from the piston to the water, and from something that lifts the object in the larger opening), $Delta V=A_1x = A_2y$.
$$y=frac{A_1x}{A_2}$$
Since, $A_2 >A_1$, clearly, $y<x$.
$endgroup$
add a comment |
Your Answer
StackExchange.ready(function() {
var channelOptions = {
tags: "".split(" "),
id: "151"
};
initTagRenderer("".split(" "), "".split(" "), channelOptions);
StackExchange.using("externalEditor", function() {
// Have to fire editor after snippets, if snippets enabled
if (StackExchange.settings.snippets.snippetsEnabled) {
StackExchange.using("snippets", function() {
createEditor();
});
}
else {
createEditor();
}
});
function createEditor() {
StackExchange.prepareEditor({
heartbeatType: 'answer',
autoActivateHeartbeat: false,
convertImagesToLinks: false,
noModals: true,
showLowRepImageUploadWarning: true,
reputationToPostImages: null,
bindNavPrevention: true,
postfix: "",
imageUploader: {
brandingHtml: "Powered by u003ca class="icon-imgur-white" href="https://imgur.com/"u003eu003c/au003e",
contentPolicyHtml: "User contributions licensed under u003ca href="https://creativecommons.org/licenses/by-sa/3.0/"u003ecc by-sa 3.0 with attribution requiredu003c/au003e u003ca href="https://stackoverflow.com/legal/content-policy"u003e(content policy)u003c/au003e",
allowUrls: true
},
noCode: true, onDemand: true,
discardSelector: ".discard-answer"
,immediatelyShowMarkdownHelp:true
});
}
});
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
StackExchange.ready(
function () {
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fphysics.stackexchange.com%2fquestions%2f472256%2fwhy-doesnt-a-hydraulic-lever-violate-conservation-of-energy%23new-answer', 'question_page');
}
);
Post as a guest
Required, but never shown
2 Answers
2
active
oldest
votes
2 Answers
2
active
oldest
votes
active
oldest
votes
active
oldest
votes
$begingroup$

Displacement in both sides is not same. If on one side of lift the area is $A_1$, and on other side it is $A_2$, and we apply a force $F_1$ on one side to distance $d_1$ then volume decreased in one side is $=A_1 times d_1$
Equal amount of volume will raise in the other side.
So $$A_1 times d_1=A_2 times d_2$$
$A_1 not= A_2$, so $d_1 not=d_2$.
Actually, we need to apply the little force $F_1$ for a greater distance $d_1$.
New contributor
Broly is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
$endgroup$
add a comment |
$begingroup$

Displacement in both sides is not same. If on one side of lift the area is $A_1$, and on other side it is $A_2$, and we apply a force $F_1$ on one side to distance $d_1$ then volume decreased in one side is $=A_1 times d_1$
Equal amount of volume will raise in the other side.
So $$A_1 times d_1=A_2 times d_2$$
$A_1 not= A_2$, so $d_1 not=d_2$.
Actually, we need to apply the little force $F_1$ for a greater distance $d_1$.
New contributor
Broly is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
$endgroup$
add a comment |
$begingroup$

Displacement in both sides is not same. If on one side of lift the area is $A_1$, and on other side it is $A_2$, and we apply a force $F_1$ on one side to distance $d_1$ then volume decreased in one side is $=A_1 times d_1$
Equal amount of volume will raise in the other side.
So $$A_1 times d_1=A_2 times d_2$$
$A_1 not= A_2$, so $d_1 not=d_2$.
Actually, we need to apply the little force $F_1$ for a greater distance $d_1$.
New contributor
Broly is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
$endgroup$

Displacement in both sides is not same. If on one side of lift the area is $A_1$, and on other side it is $A_2$, and we apply a force $F_1$ on one side to distance $d_1$ then volume decreased in one side is $=A_1 times d_1$
Equal amount of volume will raise in the other side.
So $$A_1 times d_1=A_2 times d_2$$
$A_1 not= A_2$, so $d_1 not=d_2$.
Actually, we need to apply the little force $F_1$ for a greater distance $d_1$.
New contributor
Broly is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
edited 7 hours ago
MarianD
242128
242128
New contributor
Broly is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
answered 7 hours ago
BrolyBroly
401113
401113
New contributor
Broly is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
New contributor
Broly is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
Broly is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
add a comment |
add a comment |
$begingroup$
The displacement produced is not the same. That is why, energy is conserved.
When you apply force on one side of the opening (with smaller $A$, i.e. $A_1$), the displacement in the piston that does the work on the water is say, $x$. The displacement on the other side of the lift with $A_2$ where $A_2>A_1$, has a displacement smaller than $x$, which we'll call $y$.
What happens here is that the water absorbs energy from the piston and sends it straight to the lift on the other end with area $A_2$. The volume of water remains the same. But the displacements need not be the same.
Consider the work done $W=PDelta V$ where $Delta V$ is the change in volume. Since the first and the second openings are subjected to the same pressure (from the piston to the water, and from something that lifts the object in the larger opening), $Delta V=A_1x = A_2y$.
$$y=frac{A_1x}{A_2}$$
Since, $A_2 >A_1$, clearly, $y<x$.
$endgroup$
add a comment |
$begingroup$
The displacement produced is not the same. That is why, energy is conserved.
When you apply force on one side of the opening (with smaller $A$, i.e. $A_1$), the displacement in the piston that does the work on the water is say, $x$. The displacement on the other side of the lift with $A_2$ where $A_2>A_1$, has a displacement smaller than $x$, which we'll call $y$.
What happens here is that the water absorbs energy from the piston and sends it straight to the lift on the other end with area $A_2$. The volume of water remains the same. But the displacements need not be the same.
Consider the work done $W=PDelta V$ where $Delta V$ is the change in volume. Since the first and the second openings are subjected to the same pressure (from the piston to the water, and from something that lifts the object in the larger opening), $Delta V=A_1x = A_2y$.
$$y=frac{A_1x}{A_2}$$
Since, $A_2 >A_1$, clearly, $y<x$.
$endgroup$
add a comment |
$begingroup$
The displacement produced is not the same. That is why, energy is conserved.
When you apply force on one side of the opening (with smaller $A$, i.e. $A_1$), the displacement in the piston that does the work on the water is say, $x$. The displacement on the other side of the lift with $A_2$ where $A_2>A_1$, has a displacement smaller than $x$, which we'll call $y$.
What happens here is that the water absorbs energy from the piston and sends it straight to the lift on the other end with area $A_2$. The volume of water remains the same. But the displacements need not be the same.
Consider the work done $W=PDelta V$ where $Delta V$ is the change in volume. Since the first and the second openings are subjected to the same pressure (from the piston to the water, and from something that lifts the object in the larger opening), $Delta V=A_1x = A_2y$.
$$y=frac{A_1x}{A_2}$$
Since, $A_2 >A_1$, clearly, $y<x$.
$endgroup$
The displacement produced is not the same. That is why, energy is conserved.
When you apply force on one side of the opening (with smaller $A$, i.e. $A_1$), the displacement in the piston that does the work on the water is say, $x$. The displacement on the other side of the lift with $A_2$ where $A_2>A_1$, has a displacement smaller than $x$, which we'll call $y$.
What happens here is that the water absorbs energy from the piston and sends it straight to the lift on the other end with area $A_2$. The volume of water remains the same. But the displacements need not be the same.
Consider the work done $W=PDelta V$ where $Delta V$ is the change in volume. Since the first and the second openings are subjected to the same pressure (from the piston to the water, and from something that lifts the object in the larger opening), $Delta V=A_1x = A_2y$.
$$y=frac{A_1x}{A_2}$$
Since, $A_2 >A_1$, clearly, $y<x$.
answered 7 hours ago
KV18KV18
950415
950415
add a comment |
add a comment |
Thanks for contributing an answer to Physics Stack Exchange!
- Please be sure to answer the question. Provide details and share your research!
But avoid …
- Asking for help, clarification, or responding to other answers.
- Making statements based on opinion; back them up with references or personal experience.
Use MathJax to format equations. MathJax reference.
To learn more, see our tips on writing great answers.
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
StackExchange.ready(
function () {
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fphysics.stackexchange.com%2fquestions%2f472256%2fwhy-doesnt-a-hydraulic-lever-violate-conservation-of-energy%23new-answer', 'question_page');
}
);
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
12
$begingroup$
Your statement “displacement on both sides is same” is incorrect.
$endgroup$
– Farcher
7 hours ago
1
$begingroup$
do you think the levers also violate energy conservation?
$endgroup$
– user8718165
7 hours ago
2
$begingroup$
displacement means "volume", right?
$endgroup$
– JEB
5 hours ago
2
$begingroup$
@JEB hits the point. Displacement here means a distance moved and not the volume displaced.
$endgroup$
– JimmyB
5 hours ago