Direction Definition and 999 Threads

I understand that the current is going rightward because of the negative sign in the equation above, but why is the current increasing not decreasing? The current doesn't stay constant because it changes with the time based upon the equation above again.

My understanding of static friction is that it is a resistive force in response to an applied force. I recently read the following example. A rope of uniform density, length L, is fastened to a plane with incline angle “theta” along its length. The question asks for the tension at the top of...

I am very confused when textbooks say the direction of Angular velocity is perpendicular ot radius and theta for that matter direction is in perpendicular direction. I know this comes from cross product rule but what is the meaning of Angular velocity and Angular momentum directing in upward...

Unfortunately, I have no idea about a possible solution.

How do I know is this object at rest,moving to the left or moving to the right ?

I didnt understand the question. The magnitude is 2(pie)/wavelength. I get 78500 rad/cm which is pretty wrong as guess. Where would angle come into picture? Ref: https://www.millersville.edu/physics/experiments/062/index.php Shouldn't direction be like i + j + k ? So will it be like: |k|cos30...

The author of my textbook writes that a spacecraft 's "thrust in the radial direction at perigee changes the energy but not the angular momentum". Such a thrust increases the eccentricity of the elliptical orbit of the spacecraft because ##\epsilon \equiv \sqrt{1+2EL^2/\mu C^2}##, where...

Suppose we have two charged particles A and B released in the center of the Mirror (where the field is minimum). If A's velocity direction is parallel with the Magnetic field of the mirror and B's velocity is perpendicular with the field, then which one is going to get trapped, or escape, or...

In the below figure how triangle OAP is right angled. I have imagined everything but I cannot imagine angle A as right angled. Thanks!

I've been having an issue with understanding the convention of wave direction notation, here is my current understanding where I am at currently: A 3D harmonic solution to the differential wave equation can be given as: If we make some assumptions about the wave, that its amplitude is 1, its...

Hi guys, I'm being introduced to magnetism, and the direction of the Lorentz force is quite confusing since it's involving a vector product. Which method would you recommend me in order to easily deduce the direction?

I have nearly finished my homework, but am blocking at one of the simplest questions... I'm going to let ##\rho=0.094\,\Omega/m## Since the magnetic flux is increasing, then, by Lenz's law, the current in both loops is counter-clockwise. If we only look at the left loop, then...

Given a crystal basis ##\{\vec{a}, \vec{b}, \vec{c} \}##, the two lattice vectors ##\vec{r}_1 = u_1 \vec{a} + u_2 \vec{b} + u_3 \vec{c}## and ##\vec{r}_2 = 2u_1\vec{a} + 2u_2 \vec{b} + 2u_3 \vec{c}## both obviously point in the same direction whilst ##\vec{r}_2## is twice as long as...

Hello! I read that in the rest frame of a positive muon, decay positrons are preferentially emitted in the direction of the muon spin. Why is that the case? The decay is ##\mu^+\to e^+\nu_e\bar{\nu_\mu}##. Assuming that the positron is emitted at almost the speed of light, it will be a left...

The polarization referes to the direction of the electric field of a light wave which is to be one direction. The unpolarized light interacts with a material in various ways such as reflection, scattering, refraction. and each of which can transform an unpolarized light into a vertically or...

Hi I'm very stuck on what to do for these 2 questions I got wrong Can someone please help me on what triangle I need to sketch out in order to find the 2 components of forces for F1 and F2. I'm assuming you have to make use of the sine or cosine rule here I'd be grateful for any help given...

This is supposed to be very basic, where the loop is held there is a declining magnetic field in direction (-z), therefore the current is supposed to be clockwise. However in the answers it is said the the current is anti clockwise. That doesn't make sense to me. Is there a mistake in the answers?

How can I determine direction of Coriolis force for these cases?1)Ship travel at 45th north parallel to the east (course 90°)2)Ship travel at north hemisphere at course 45°3)Ship travel at equator at east (course 90°) My attempt: 1) Coriolis force is point up,vertical to the Earth surface 2)I...

As I understand, the gravity wave detection system is possible due to the change in length of the two arms, as a wave passes, thus changing the distance the light beams travel. As this distance changes, the time of flight will change in relationship to each other. This difference is then...

Hi, I apologise as I know I have made similar posts to this in the past and I thought I finally understood it. However, this solution seems to disagree on a technicality. I know the answer ends up as 0, but I still want to understand this from a conceptual point. Question: Evaluate the line...

I have a hypothesis of which I wonder if it's sound. Perhaps you guys can advise me: Suppose ##x_n\Rightarrow a_n## (logical implication) for some set X and set A. I think we have to assume a bijection. Then, if ##a_m = False##, ##x_m## should be ##False##, right? So, in case of a bijection...

I want to understand the direction of force on the voice coil, if the conductor is straight line it is easy to find the force direction. In the case of the diagram i shown below, for the curved surfaces i should take tangential to the surface at every point. Am i correct? So for position 1 since...

Taking upward direction as positive why will the acceleration be -9.8? Is it due to the curve of the graph?

I've seen a lot of Youtube clips and listened to podcasts recently on cosmology and quantum physics and something that has come up frequently that I don't understand is descriptions of time. Specifically Sean Carroll on various podcasts and Carlos Ravelli (when he finally got to the point). 1...

My question is: given a rigid body which interacts with a surface, what's the direction of the normal force? Because, as the word says, it has to be normal to the surface. But when treating problems of a vertical rod which is slightly pushed and forms an angle ##\theta## with the surface, some...

I am struggling with the angles. Since the conducting wire is moving down for it to be stand still, the force should be opposing it, hence the current should be from Right to Left. I am confident of the Force direction and its value is if ## I ## is the current ##F = ILB (N)## since L and B...

Earth moves through space in a certain direction at a certain speed. Moving faster slows down your clock while moving slower increases your clock. Does this mean that the direction your moving in has an effect on time dilation? In other words, if you move along with the earth’s initial speed...

i tried to draw the directions of the parameters The direction of B is clear since then the Force will be in the positive X direction. I am bit confused with the direction of Force, how would i draw it and the components. Is the gravitational force i have drawn is correct? Do we have better...

Hello! If I have an atom traveling with a given velocity and I ionize it in flight, will the electron remain at the place of ionization, or it will travel at the same speed along with the resulted ion? Thank you!

Is there a way to modify a thin overhead LED light fixture that fits over a ceiling box to make the direction of the light easily adjustable? Perhaps add some sort of adjustable shade to it? In remodeling a bedroom, I'd like to install ceiling boxes ( e.g...

For the region where V = 0, solving the schrodinger equation leads to the above value of wave function, psi = sqrt(2/L) sin(pi x/L) Since in the qus. it is not stated about the 'direction of movement' only restricted to +x direction, I think that the probability will be 1/2. And finding the...

First and foremost, thank you so much for your help! I'm new to Physics Forums, and this is my first post. I thought I understood the problem, but as I moved on to the subsequent parts of it became apparent that I was missing something. I set up my ##F = ma## equation as below, and solved that...

I have not tried to make any calculation. It's nonsense, because I don't understand the statement. The first vector points to the west. Given a two dimensional coordinate system, the first vector is pointing to the left. I imagine geographical coordinates, north (+y), south (-y), west (-x), and...

So I have a cube in 3d space and this cube is made out of 8 coordinate points at each corner. Now I have a temperature reading at each point of these corner points. Inside the box I have another point, I want to be able to use the information from the 8 points surrounding the the one middle...

If we use a spear or gun with bullet, then we should aim lower than the position where we see the fish because due to refraction, the apparent position of the fish in the lake will be higher (nearer to the surface) than the actual position of the fish. But if we use a laser gun, I think we...

A square table of size 1001x1001 is filled with the numbers 1; 2; 3; ... ; 1001 in such a way that in every row and every column all those numbers appear. If the table is symmetric with respect to one of its diagonals, prove that in this diagonal all of the numbers 1; 2; 3; ... ; 1001 appear.

My answer was correct, however my direction was different from the textbook. I have checked my work a few times ,but not able to find out what I did wrong. Could anyone tell me what I did wrong. Thank you in advance for your help.

I think i read somewhere that jet engine shaft is neutral,because forces at turbine and compressor cancle out,so that mean axial berings don't have force on it in direction of thrust!? (this can't be true,becsue in that case thrust will be zero...) But if this is true ,against what pressure...

For my understanding, to move to the coolest place, it has to move in direction of -∇f(x,y) How can I find the value of 'k' to evaluate the directional derivative and what can I do with the vertices given.

I had a question from the magnetic dipole thread that was posted earlier today, but it's a bit more mundane. The torque on a magnetic dipole, using a right handed cross product is ##\vec{\tau} = \vec{\mu} \times \vec{B}##. The work done during a rotation is $$W = \int \vec{F} \cdot d\vec{r} =...

What is the direction of the frictional forces especially when there are 2 forces acting on an object? (see attached Image)

I want to say [the bodies is under gravity field]: There cannot be torque alonge AB "since it is pivoted" There cannot be torque alonge AB "since it is pivoted" i think i am missing something.

I do not understand part b. I know that x180/pi changes the value into a degree, but i do not understand what's going on inside the bracket. And how did the equation calculated the direction?

$\dfrac{dy}{dx}=\dfrac{4y-3x}{2x-y}$ OK I assume u subst so we can separate $$\dfrac{dy}{dx}= \dfrac{y/x-3}{2-y/x} $$

Hey I am trying to learn how waves move in time and I am not sure how to solve the following question. Can someone please guide me through it.

I have a vector field which is originallly written as $$ \mathbf A = \frac{\mu_0~n~I~r}{2} ~\hat \phi$$ and I translated it like this $$\mathbf A = 0 ~\hat{r},~~ \frac{\mu_0 ~n~I~r}{2} ~\hat{\phi} , ~~0 ~\hat{\theta}$$(##r## is the distance from origin, ##\phi## is azimuthal angle and ##\theta##...

I'm trying to compute a 2D Heat diffusion parabolic PDE: $$ \frac{\partial u}{\partial t} = \alpha \{ \frac{\partial^2 u}{\partial x^2} + \frac{\partial^2 u}{\partial y^2} \} $$ by the ADI method. I am actually trying to go over the example in this youtube video. The video is in another...

Please help me to find the position P and whether it will work in this solution by knowing the position. (The question, my solution and thought in the image)

I'm often got confused about why the direction of pseudo force is taken opposite to the direction of motion of the body. As specific, I have this question. In this, I didn't understood about why the direction of pseudo force is taken in right, in the diagram of solution provided to this...