# Questions tagged [vectors]

Geometric object with magnitude (length) and direction.

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### Multiplying a force vector by rotated unit vector produces strange results [closed]

I'm by no means an expert in math, what I'm trying to do is to Isolate a force aligned with a vehicle in a game (specifically to do a directional friction). the equation is simple I take a vector $v_1$...
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### To find out if 3 vectors are coplanar or not [migrated]

3 vectors A,B and C are given. We have to find out if they are coplanar. I have been taught to find the cross product of any two of the 3 vector like B×C. This cross product will be perpendicular to ...
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### Is there a spacetime vector projection representation for the wave function? [closed]

Is it possible to represent the wave function as a spacetime vector projection? In QM, the inner product of the wave function is given by $\langle \Psi | \Psi \rangle$. Is it possible to have a "...
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### On which side of object should friction force be drawn on a vector diagram?

Let's say a box is moving to the right and friction is slowing it down. The friction force vector pointing to the left and the object moving to the right, should the vector be drawn on the left side ...
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### Boat-river problem [closed]

A river flows from east to west at 4 km/hr. From the north bank of the river, the first boat starts traveling straight towards the other bank at a speed of 10 km/h. The second boat starts moving along ...
1 vote
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### Combing different SHMs which are in the same direction

Our teacher taught us this method for combining different SHMs he didn't really give a lot of formal defination etc he just said us about the algorithm to solve it as shown in the picture what seemed ...
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### Why are 2D inertia tensors $2\times 2$ matrices when 2D objects can only rotate around one axis?

Why is the 2D inertia matrix defined as $$\begin{bmatrix}I_{xx}&I_{xy}\\I_{yx}&I_{yy}\end{bmatrix}$$ and not just a vector 2 or scalar? I saw something saying that $I_{xx}$ is the moment of ...
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### From where does the expression of the tangential accerelation come from?

I've seen so many times that the expression of the tangential acceleration is known to be: $$a_t=\ddot{s}$$ but from the expression of the acceleration in spherical coordinates, in the tangential ...
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### Symmetry of Crystalline Lattice

In the book Solid State Physics by Kittel, it is written in Bravais Lattice's definition that "the arrangement of atoms in the crystal looks the same when viewed from the point r as when viewed ...
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### Tensor to vector notation [closed]

I have the expression $$\partial_{k} \left( a^{-1} b^{2} \eta^{j k} \partial_{j} G \right) = a \vec{\nabla} . \left( a^{-2} b^{2} \vec{\nabla} G \right)$$ Is the transition from tensor to vector ...
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### Why does force perpendicular to the velocity change only its direction; not the speed?

While analyzing the case of a force and consequently an acceleration acting perpendicular to the velocity of a given body, I do understand that force's component along the velocity will be 0 causing ...
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### Teacher told us we're not allowed to write negative vectors, is this correct or not?

The question is a bit vague, so I apologize for that. To properly explain what I mean, I'll use an example. Let's say we've got two forces going left and right. $F_1$ is $20 \, \text{N}$, and will be ...
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### Question about velocities in different reference frames

Suppose $\hat{x^{'}}, \hat{y^{'}}, \hat{z^{'}}$ are the unit vectors of an inertial frame and $\hat{x}, \hat{y}, \hat{z}$ are the unit vectors of a frame which maybe accelerating, rotating, whatever....
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### Doubt in fictitious forces chapter in Morin

The question is this - I know 2 is what the non-inertial frame measures, but isn't $\frac{d\mathbf{A}}{dt}$ the real thing, the physical thing? And you can write that too in terms of the unit vectors ...
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### Transformations that preserve the metric [duplicate]

I know that transformations that preserve the metric (like the Lorentz transformation, or rotations) have the property: $$S^T \eta S = \eta$$ However, I'm getting: $S^TS = I$ and I'm not sure why: \...
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### Is $Fx = Fcosθ$ or $Fx = Fsinθ$? [closed]

Sorry for the stupid question, but I've learned that Fx = Fsinθ. But then I've seen in the internet some websites saying that it was actually Fx = Fsinθ, and others saying it was Fx = Fcosθ. What ...
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