Questions tagged [displacement]

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Is linear momentum times distance any meaningful quantity? $\vec{r} \cdot \vec{p}$ or $pr = mvr$ comparing to $\vec{r} \times \vec{p}$

Angular momentum is$$ L=\vec{r} \times\vec{p}$$ I was wondering if the dot product has any meaning: $$ ?= \vec{r} \cdot \vec{p}$$ Does it mean anything? It could also be rewritten like $ rp$ or $\...
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-1 votes
1 answer
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Energy and force relation

So in simple machine we apple less force with more displacement to exert same energy as the load need so if energy is related to tiredness i.e. more energy you lose more tired you feel but by applying ...
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1 vote
3 answers
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How to interpret a displacement-position graph?

I have a good understanding of Displacement-time graphs and position-time graphs and how to interpret them. I take the IB diploma and came across this question from a 2009 paper with a displacement-...
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1 answer
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Formula for work done for both conservative and non-conservative force are different?

We know that the formula for Work Done by an constant force is W.D = Force x displacement x (cosine of angle between force and displacement). Situation: A mass m travels 10 meters towards  +ve axis ...
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Question regarding Work Done [duplicate]

I am studying Classical Mechanics ,but I still find the definition of Work non-intutive ,I am a bit ashamed to say this . Work Done is $dW=F.dr$. The Force acting on the body is changing the position ...
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2 answers
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How can work done by a person be negative, e.g. in lowering a book? [duplicate]

I am holding a book of mass 0.5 kg in my right hand at a height of 1 m from ground level. The book is lifted to a height of 1.5 m above ground and then brought down to its original height of 1 m. The ...
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2 answers
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Time dependence of generalized coordinates and virtual displacement

The Cartesian coordinates of particles are related to the generalized coordinates via a transformation (for the $x$ component of the $j$-th particle) as: $$x_j = x_j(q_1, q_2, \ldots, q_N, t)$$ What I ...
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1 vote
4 answers
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Work and Force x Distance Relation

I'm trying to understand the work-energy theorem, and I understand the relation here: $$W = \int \vec F \cdot d\vec{x}$$ But its the process that I need help clarifying a hypothetical. Work is equal ...
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Why is there no phase shift between pressure and displacement in spherical sound waves?

I know this question was already stated, but for me it didn't provide an intuitive answer. So can someone elaborate why there is no phase shift between displacement and sound pressure close to the ...
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Why is it more crucial to consider velocity field than displacement field in Fluid Mechanics?

Why is it more crucial to consider velocity field rather than displacement field in Fluid Mechanics?
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Why do we decompose the boundary surface in Initial boundary-value problems?

Just started to learn about initial boundary-value problem, and I have came across the concept of decomposing the boundary surface into to disjoint parts, one for stress tensor field and another for ...
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1 answer
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Defining a Finite Displacement Vector Using Polar Unit Vectors

I believe I understand how to define positions using polar unit vectors. However, I'm stuck on how to define finite displacements using said vectors. I keep bumping up against the fact that such a ...
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3 answers
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Simple Harmonic Motion: Displacement formula [closed]

In Simple Harmonic Motion, the formula for Displacement is : $$x=A\mathrm{sin}(ωt-Φ)$$ So, if the value of $Φ$ (phi) is not given in the question, should I use "Zero" as the value of phi? ...
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1 answer
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How to know which solution is physical?

When solving the expression for displacement of an accelerating object and solving for the time variable: $$v_it+\frac{1}{2}at^2=d$$ $$v_it+\frac{1}{2}at^2-d=0$$ $$t=\frac{-v_i\pm \sqrt{v^2_i+2ad}}{a}$...
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2 votes
4 answers
118 views

Why do we need position vectors?

Position vector is a vector which defines location. It is also the only kind of vector which can't be moved. But coordinates can also do the same work. They also define position. So why do we need ...
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2 votes
3 answers
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Is work change in energy or force times displacement? [closed]

Recently I had an exam which had the following question: For section a, I know that the work gravity has done is the force component parallel to the surface times the distance the block has travelled ...
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1 answer
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Displacement of a Projectile Along a Vector

I've been stuck on this problem for more time than I'd like to admit, and I feel like I'm overcomplicating the solution, or just not understanding the concept. I have a projectile in motion in three-...
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How do we show that the work done by a variable force (in one dimension) is the area under the $F$ vs. $x$ curve?

In my physics textbook, to show that work is the area under the $F$ vs. $x$ curve, the author first writes the relation $dw = F dx$. This part makes sense to me. From there, the author writes, $$W = \...
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1 answer
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Question about the value of angular displacement [closed]

Can angular displacement be greater than $2\pi$ radians? Is $5760$ radians correct here or should we do something like this: $\frac{5760}{2\pi} = 916.732472209$ $0.732472209 \cdot 2\pi = 4....
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1 answer
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Which distance will the rocket fall at? [closed]

The first rocket in the world had a mass of 2 kg (without the charge). When the charge bursted, 200 g of explosive gases were thrown out at the speed of 600 meters per second. Which distance will the ...
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1 answer
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Mechanics queries

Why the work done by internal forces is independent of frame of reference? Since the work done by a body is the dot of force and displacement and displacement is a frame dependent quantity, then how ...
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Clarification on the displacement in the definition of Work

I'd like to ask a question about work. The definition of work gives us a way to calculate the work done by a force along a path but in practice it's not always clear what path to take in consideration....
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Angular displacment and "normal" displacment of a minutes hand in a clock/watch

Note : i'm using "normal" because i'm not really sure what is its correct name, i suppose linear is more correct. as a backstory, we were solving questions in today's class and this came up (...
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1 vote
6 answers
123 views

Is the energy formula 'force multiplied by displacement' ($E=W=Fs$) correct? Why? [closed]

Is there a reason that the definition of energy is work, and work is defined as force multiplied by displacement ($E=W=Fs$)? It seems to me a strange formula. 'Momentum' is what puts a motionless mass ...
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3 answers
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Different equation is given for "position"

$$s=ut+\frac{1}{2}at^2$$ Assuming, $u=0$ $$s=\frac{1}{2}at^2$$ $$a=\frac{2s}{t^2}$$ So I got a function for acceleration. $$v=u+at$$ $$v=\frac{2s}{t} \tag{1}$$ In reality I know that $s=vt$ when ...
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Paradox in the Kinematic Equations of Motion

The 5 equations of motion have been chosen such that from the 5 variables of motion: $s$, $u$, $v$, $a$ and $t$; each equation, exclusively omits one of these. This allows us to only ever require the ...
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1 answer
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Finding the angle that gives longest path for projectile motion using the average speed over the vertical displacement of object

For projectile motion, let's say a ball is launched at an angle a with respect to the horizontal, upwards. If I want to find an expression for the length of the path travelled by the ball before it ...
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2 votes
0 answers
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Why is there no work done by the wall on the person pushing it? [duplicate]

I revisited the basics of Physics and while studying work done, I came across the following question: You stand on roller skates facing a wall. You push against the wall and you move away. Discuss ...
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How to compute the Ocean tidal effect by giving the lat+long for specific location on a website?

I am quite new in this and interested in computation of contribution of the Ocean tidal gravity. I am following the website (http://massloading.net/ondemand_form.html) to get the data but I want to ...
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1 vote
2 answers
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Why is position proportional to time squared?

Now I know some of the obvious answers to this, such as if you integrate the acceleration twice, you’ll get time squared, but what I’m really looking for is more of an intuitive answer. One of the ...
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How can I calculate acceleration from displacement and time?

How can I calculate acceleration from displacement and time, assuming a velocity at rest? Is there any formula to do so?
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3 votes
3 answers
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How do acceleration, velocity, and displacement affect/relate to eachother?

I have been wondering this since learning about position, velocity, and acceleration vs time graphs but can't put numbers/equations to it. I know that acceleration acts to change velocity, shown by ...
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Sign convention for relative displacment

If an object A is $X\ \mathrm m$ behind B,than the relative displacemnt of A wrt B would be $-X$. However is object A was moving towards B(at rest) at a rate of $Y\ \mathrm{m/s}$, then $$V_{ab}=+Y-0=+...
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Virtual displacement consistent with constraints or not

Are virtual displacement consistent with the constraints? It is claimed that (i) a virtual displacement δr is consistent with the forces and constraints imposed on the system at a given instant --1; ...
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1 answer
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Why is displacement shown in the picture below $y1-y2$ and not $y2-y1$? [closed]

I am having a hard time understanding why is the displacement in the formula of work shown in the image y1-y2? Isn't displacement final value - initial value?
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2 answers
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Variables in rectilinear motion

I wrote a post few days earlier on circular motion but it seems i still haven't got the hang of it yet. When is this equation actually true? $s=ut+\frac{1}{2}at^2$ Suppose velocity is given by $v=t-2$ ...
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How to get acceleration from motion curves under position time ($x$-$t$) graph and speed? [duplicate]

In this video by Physics Wallah, he said that, In a displacement time graph, if the concave is upward, then the acceleration is positive, and if concave is downward, then the acceleration is negative....
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1 vote
1 answer
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Why could we only divide the displacement $x$ into arbitrarily many subintervals instead of dividing the force $F$ when calculating the work done? [duplicate]

The definition of work done in moving the object from a to b using integral is $$W=\int_{a}^{b}f(x) \,dx$$ where the force F is a function of displacement x, namely $F=f(x)$ It is makes so much sense ...
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1 answer
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Why do we consider that if initial & final positions are same then displacement of an object is Zero?

I was thinking on a basic high school problem about motion on one axis and came across one of those problem where displacement is zero because final and initial positions are same. My question is that ...
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1 vote
2 answers
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Is it possible to have non-zero displacement at $t = 0$?

Consider the attached graph. It shows the displacement at $t = 0$ to have some non-zero value. Is this physically possible? This is what I think: The displacement vector of a particle between times $...
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-3 votes
2 answers
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Why is work done force times displacement? [duplicate]

Why is work done the product of force and displacement? Why not force and time?
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0 votes
1 answer
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What does the $y$-axis in quadratic equation graph when solving for the vertical displacement mean?

A projectile is shot from a cannon with an initial velocity of 20 $\frac ms$ from the base of an incline surface of angle 25°. The angle of projection with the incline surface is 10°. How far will the ...
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0 answers
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Why does using Displacement vector doesn't give the correct result for the surface charge density of an infinite dielectric slab below a point charge

Find the force on a point charge $q$ placed a distance $d$ above the XY plane with the region $z<0$ filled with dielectric with susceptibilty $\chi_{e}$. (From Griffiths EM, Example 4.8) The ...
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3 answers
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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 ...
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1 answer
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Why should we integrate to find displacement instead of directly plugging in $t$ for displacement function?

context:preparing for jee, chapter kinematics. text book problem given $v = 2t^2$ find $x$ at $t=2s$ if at $t = 1s$, $x= 3m$ My solution integrating v to find displacement fucntion $$ x(t) = \int2t^...
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-1 votes
2 answers
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Why do we use $\frac12(v_f+v_i)$ in the kinematic equations?

I find it confusing that we have to use the average of the velocity instead of the final velocity. Can someone explain to me why $$s = \frac12(v_f+v_i)t$$ is true?
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Spring system forces and displacement

I am trying to understand this system. A friend added to my confusion by stating the springs will not see all of Force B, they will only see all of Force B when the springs bottom out. To me, by ...
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-2 votes
2 answers
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What is definition of displacement in context to kinematics? [closed]

I want explanation of word particular here. The change in position of a body in a particular direction is called displacement.
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1 answer
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How should the displacement-time graph be drawn (if anything should be drawn)?

Let's say I have a particle that goes from A to B, hits a wall at B with velocity $1.4 \mathrm{m}/\mathrm{s}$ and starts to go back to A with velocity $-1\mathrm{m}/\mathrm{s}$ starting from B. So ...
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4 answers
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Can you use the SUVAT equations of motion to draw a displacement-time graph? [closed]

Can you use the SUVAT formulae of motion to draw a displacement time graph or should you integrate the graph you get from a velocity-time plot first? And why? If i have S = 4.4 U = 3 V = 1.4 A = -0.8 ...
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