Geometric object with magnitude (length) and direction.

learn more… | top users | synonyms

0
votes
2answers
31 views

How to determine the angle of a force?

So when an object is on an incline, I know how to get the magnitudes of the forces but I am having trouble with the direction. Here is an example: So you have calculated the force of friction, ...
0
votes
0answers
27 views

What is the difference between triangle law and parallelogram law of addition of vectors…? [migrated]

And if they both are same then why they are used differently? Pls give detailed answer
-1
votes
0answers
25 views

What is a state vector? [on hold]

Please can someone give me an intuitive expansion of a state vector? For example, what are they, functions? What does one state vector represent? One does it mean to add two state vectors? etc. I have ...
1
vote
1answer
31 views

What's the physical meaning of change in momentum vector?

If I there is a initial momentum of 10Ns upwards, and final momentum of 10Ns to the right, I can find the difference in momentum by drawing a triangle and finding the resultant vector. But, how is ...
-6
votes
0answers
16 views

Vector and motion in 2D [on hold]

Q. A particle is moving in a circle of radius r centre at O with constant speed v the change in velocity moving from A to B ( angle AOB = 40°) is : A. 2v cos40° B. 2v sin40° C. 2v cos20° D. 2v sin20° ...
0
votes
0answers
30 views

Initial position and velocity given, force given. Find the trajectory of the particle [on hold]

If a particle of mass m at time t=0 has velocity v = u j position r = -a i Force acting on the particle is F = $-(mv^2/a)$(R/R) (R is the position vector, v is the velocity vector) Find the ...
2
votes
3answers
147 views

Deriving cross product from angular momentum algebra

Is it possible to derive: \begin{equation} \hat{L}=\hat{r}\times \hat{p} \end{equation} from the angular momentum algebra: \begin{equation} [\hat{L}_i,\hat{L}_j]=i\ \hbar\ \epsilon_{ijk}\hat{L}_k\ ? ...
-2
votes
0answers
24 views

Projectile motion with mass, find the range [closed]

a missile has the position vector P(t) = ht i + t(v − 5mt) j. where m is the mass (kg) of the missile, and h/v is the horizontal/vertical speed (respectively) the missile is launched with. Using the ...
0
votes
1answer
25 views

Why is parallel component of velocity along position vector considered rate of change of position?

If you have a position vector and a velocity vector of a particle, then the component of velocity vector along position vector is the rate of change of distance of the particle from the reference ...
2
votes
2answers
33 views

what does magnetic field vector mean?

I am trying to understand what a magnetic field vector tells us about the magnetic field. I understood that a vector is just a representation of a point and how much it is moved in x,y and z direction ...
3
votes
2answers
75 views

Making sense out of covariance and contravariance

I just read about co- and contravariant vectors and I am not sure that I got it right: If we imagine that we have a n-dimensional manifold $M$ then a tangent space is spanned by the vectors ...
0
votes
1answer
39 views

Is the flux through A the same as the flux through B?

In the figure below, the amount of field lines through A is the same as the amount of field lines through B, but can you say the flux through A is the same as the flux through B as well?
-4
votes
0answers
24 views

Net force acting on the block along the inclined path can be mgcos(theta)? [closed]

If we take the angled marked with red curve then the net force along the x axis or inclined path comes out mgcos(theta) is is correct?
-1
votes
1answer
20 views

Calculating uniform angles between 2 vectors [closed]

If I have two vectors, say: [100] and [101] and I want to calculate two angles between them, uniformly distributed, would it just be: [1 0 0.33] and [1 0 0.66]? So, [100] = 0 degrees [101] = 45 ...
1
vote
0answers
26 views

How do I show $e_r$ and its first- and second time derivative?

What does a charge q moving in a circular orbit with a constant velocity (a "rotating charge") and a stationary observer that measures the E field look like? And how do I show $e_r$ and its first- and ...
1
vote
2answers
87 views

Derivation of Jefimenko's Equation in Jackson's EMT book

I have been trying to understand the derivation of Jefimenko's equation in Jackson on p.246-247 which can be seen in the photographs attached. First of all I did not fully comprehend the ...
1
vote
0answers
26 views

Displacement Vectors [closed]

Displacement vectors of 3m and 5m in the same direction combine to make a displacement vector. How long is it? What is a displacement vector and how do I calculate this?
0
votes
2answers
39 views

Why taking components of a component of a vector is invalid?

Suppose there's a force $F$ of magnitude 10 newtons in the direction of positive y-axis acting on a particle A. I know that the particle would not experience any force in the positive x-direction ...
1
vote
2answers
31 views

Finding the magnitude of Two Vectors [closed]

Vector C has a magnitude 23.4 m and is in the direction of the negative y-axis. Vectors A and B are at angles α = 44.4° and β = 27.7° up from the x-axis respectively. If the vector sum A+B+C = 0, what ...
0
votes
0answers
22 views

How to convert $V \otimes W^*$ to a matrix space? [migrated]

Namely let's say we have chosen basises $e_1, e_2, ... e_k$ for $V$ and $j_1, j_2, ... j_n$ for $W$. Now, since we can always just convert them separately, and then add the matrixes, how we represent ...
0
votes
2answers
41 views

Direction of electric field lines and electrostatic force

Direction of electric field and electrostatic force should be same by the equation $$\vec{F} = \frac{k q q_0}{r^2}$$ Electric Field $$\vec{E} = \frac{k q}{r^2}$$ Let us suppose that there is a ...
0
votes
2answers
63 views

When does $\mathbf n\times(\nabla V_2-\nabla V_1)=0$ imply $V_1=V_2$

I was reading a paper on electrohydrodynamics which has the following sentence (in my own words): At the interface/boundary, the requirement of continuity of the tangential component of the ...
0
votes
1answer
16 views

How to find one of the vectors when we know the other, the angle between the vectors and the result? [closed]

We're given that the result of the two vectors $a$ and $5$ is $7$ and the angle between the two vectors $5$ and $a$ is $60$ $degrees$. How do we calculate the of the vector $a$ ? I used $R^2 = P^2 + ...
0
votes
0answers
17 views

Vector Problem - Resultant [migrated]

This was a problem asked to me in a science quiz: Given |A|=10,and R=A+B.Hence what are the possible values of |B| ? I said that since the angle between vector A and vector B can be anything ...
2
votes
1answer
37 views

ϕ-component of equation of moition: proving a relationship [closed]

I have the following velocity vector (in spherical polars): \begin{equation} \textbf{v} = u \hat{\textbf{r}} + v_{\phi}\hat{\boldsymbol\phi} \end{equation} Where $u(r) = u$ and $v_{\phi} (r) = ...
0
votes
1answer
28 views

Resolution of force vectors

For example in a simple pendulum problem.. the forces that act on the bob are tension and gravitational force. but while the resolving the vectors to find T(tension) at any given angle x with the ...
0
votes
3answers
68 views

Tension on a string

A string is attached at both extremities and put under tension $T_0$ at rest. We know that if we pull the string upwards from the middle, the tension will increase. But why is it that, admittedly, ...
0
votes
1answer
50 views

Difference between Speed and Velocity

What is the difference between Speed, Velocity and Acceleration? Could any one describe it pictorially?. I am more over confused even after investigating many times. I am unable to relate myself ...
0
votes
2answers
105 views

Is a vector and a unit vector dimensionless

Lets say I have a position vector $\vec r$. Is it dimensionless or does it have a dimension of length i.e $[L]$. Also does the unit vector $\hat r$ have a dimension?
1
vote
1answer
36 views

Is the Mass flow rate (Mass flux) a scalar quantity?

Wikipedia states that mass flow rate is a scalar quantity, however Mass Flow Rate= Density x Cross Sectional Area x Velocity and velocity is a vector quantity, so this would imply Mass Flow Rate is ...
-1
votes
1answer
71 views

A particle is constrained to move around the unit circle in the xy plane according to (x,y,z) = (cos(t^2),sin(t^2),0) t >= 0 [closed]

A particle is constrained to move around the unit circle in the xy plane according to (x,y,z) = (cos(t^2),sin(t^2),0) t >= 0 At what point should the particle be released to hit a target of (2,0,0)? ...
2
votes
4answers
150 views

Normal Vectors to these Hypersurfaces on a Lorentzian Manifold

With respect to the coordinates $(x^{0},x^{1},x^{2},x^{3})=(v,r,\theta,\phi)$, we have the following components of the metric tensor: $\begin{bmatrix} g_{00} & g_{01} & g_{02} & ...
3
votes
2answers
94 views

Why is the “complete metric space” property of Hilbert spaces needed in quantum mechanics?

I have been learning more about Hilbert spaces in an effort to better understand quantum mechanics. Most of the properties of Hilbert spaces seem useful (e.g. vector space, inner product, complex ...
0
votes
1answer
43 views

How can Bernoullis be solved without Vectors [duplicate]

Some time ago I asked a question why Dynamic pressure is considered scalar. Why is the dynamic pressure not a vector quantity? This still puzzles me so I hope to give a scenario that doesn't make ...
11
votes
7answers
252 views

How can a set of components fail to make up a vector?

Many books in Physics insist to define vectors are objects with components with the property that the components transform in a proper way under a change of coordinates. Now, in mathematics, on the ...
1
vote
2answers
99 views

Relation between Vector space $V$ and its dual $V^{*}$ [closed]

I asked the same question in Math.SE, but I was suggested to ask it here as well. I am studying relativity, and as you know the theory extensively uses the notion of covariant and contravariant ...
0
votes
1answer
29 views

Electric Flux - Vector Components

How is $vcos(\theta)$ the perpendicular vector? I think I'm missing something fundamental in my trig and vector knowledge...
1
vote
0answers
21 views

Write the force as a sum [closed]

We suppose that a force $\overrightarrow{F}$ (for example, the gravity) is applied vertically downwards to an object that is placed at a plane which has an angle of $45^{\circ}$ with the horizantal ...
1
vote
1answer
95 views

Quantities that have magnitude and direction but do not obey the parallelogram law [closed]

Back in college, when I'm learning about Vectors, I remember the text book saying.. There are certain quantities that have Magnitude & Direction but doesn't follow the Parallelogram Law of ...
0
votes
1answer
49 views

vector and position and acceleration [closed]

I really need your help with two problems. Consider a moving object that can be described by the position function r(t) = [(8.00m/s )t-[( 4.50m/s^3 )t^3 ]î +(− 2.00 )t^2+10.0m]ĵ In unit­vector ...
1
vote
1answer
55 views

Newton's third law of motion versus Work

Newton third law of motion says that "To every action, there is always an equal and opposite reaction". The vector study tells us that if two vectors are of same nature and equal magnitude but ...
0
votes
1answer
99 views

Basic question about angular momentum

I've learned that the angular momentum of an object rotating about a fixed axis is $I \omega $. Also, in absence of external torques, $I_1 \omega_1 = I_2 \omega_2 $ (meaning, two different events). I ...
2
votes
2answers
135 views

Is a vector field not a vector quantity?

I'm trying to make sense of Poisson bracket relation $$\{L_i,A_k\}_{PB}~=~\epsilon_{ikl}A_l,\tag1$$ where $L_i$ is $i$th component of angular momentum, $A_k$ is $k$th component of an arbitrary ...
0
votes
1answer
43 views

vector resolutions

I am learning Mechanics - motion in a plane. Is it possible to that a given vector can be resolved in infinite ways into two non-colinear vectors in the same plane? For example, I have a vector ...
0
votes
1answer
51 views

How the torque/moment-of-force can be mathematically defined?

Given the definition of torque/moment-of-force $\mathbf F$ applied in $P$ with respect to the pole $O$ $$ \mathbf M_O=\vec{OP}\times\mathbf F $$ and given that the vectors $\vec{OP}$ and $\mathbf F$ ...
2
votes
1answer
75 views

Extension of Lami's theorem

I was experimenting with the triple scalar product and forces in equilibrium when I came to this result: Consider 4 forces $ \pmb{F_i}$ for $i=1,2,3,4$. $\pmb{F_i}=F_i\hat{e_i}$ where $\hat{e_i}$ is ...
1
vote
1answer
86 views

Problem on relative motion involving wind speed .Finding the real velocity of wind?

Here is the question For a person running west at 7km/hr wind appears to blow from north-west .But when he walks towards west at 3km/hr the wind appears to blow from the north. What is the true ...
-1
votes
3answers
50 views

Vector question, differentials, Electromagnetism

I was reading this demonstration of electric potential in my book: Let $q$ be a point charge at point $P$ The Electric field created at point $M$ by $q$ is : $$\vec{E}(M) = ...
0
votes
0answers
30 views

The first term of Stokes Vector of natural light is zero?

Consider the electric field of a beam of natural light: $$ E(r,t) = E_0 \cos(k·r+wt) $$ Since this beam of light is natural, the vector E has all the components possible that satisfies: ...
1
vote
3answers
61 views

Why are $2\pi$ factors included in the definition of the reciprocal lattice?

I would like to know where the $2\pi$ factors are coming from in the formula for reciprocal vectors in reciprocal lattices. For example, in a simple cubic lattice the primitive vectors are given by ...