# Tagged Questions

Geometric object with magnitude (length) and direction.

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### 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 ...
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### 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 ...
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### 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 ...
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### Electric Flux - Vector Components

How is $vcos(\theta)$ the perpendicular vector? I think I'm missing something fundamental in my trig and vector knowledge...
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### 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 ...
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### 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 ...
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### 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 ...
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### 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 ...
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### 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 ...
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### 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 ...
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### 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 ...
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### Spacelike to timelike four vectors

First at all, let me just say that I'm not a Physicist, I study mathematics. So, I have this question. If you have a spacelike four vector, is there any transformation that could change it to be a ...
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### 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 $\mathbf F$ ...
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### 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 ...
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### 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 ...
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### Can a component of vector be greater than the vector itself?

...we have at our disposal an infinite variety of ways of resolving a given force into components. . . . The fact that any component may happen to be larger than the vector itself doesn't invalidate ...
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### Acceleration in a system equal for every body — why?

A 1 kg cart can slide frictionlessly on the table. The black weights each weigh 1 kg. The pulleys are frictionless. The task is to determine the acceleration of the cart. For the left-most weight we ...
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### Find the work done in moving an object along a vector r with a force F [closed]

$$r=3i+5j-2k$$ $$F=3i-3j+2k$$ What do I do. I know that work = force x distance. However, what vector operation should I do? I was wondering whether I should possible find the unit vector of r and ...
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### The subtle differences between angular momentum and centrifugal force?

I am a mathematician wanting to understand the differences between the concepts of angular momentum and centrifugal force. The following two ideas are clear to me from a physical point of view, but ...
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### Is instantaneous velocity a scalar or a vector?

So this is a simple question that I have been confused about. Last night I was in a discussion with a friend, and we somehow ended up on this topic. He believes that instantaneous velocity is a ...
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### Do components of force have direction when doing work?

When we get angle > 0, the x-component of force is along the direction of displacement and so their product is called Work. So the x-component of force is said to have direction of the respective ...
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### Are fundamental forces always attractive/repulsive, i.e. parallel to the separation?

If magnetic monopoles existed it would not be the case - the forces on an electron and a magnetic monopole passing by each other would be at right angles to the vector connecting the two particles! ...
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### Change of vectors [closed]

We have two vectors $F1$ and $F2$ as shown in figure. The change of vectors is shown as $F2-F1$. Why it is it rather than taking negative of vector $F2$ i.e. $-F2$ and then adding it by head-to-tail ...
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### Why do physics students find vectors so difficult to deal with? [closed]

When I teach introductory physics to undergraduates, I find that although the classes are frequently split into "algebra-based" and "calculus-based" sections, the most difficult concept for any of ...
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### Net force of the following? [closed]

The following objects are attached to one another and have difference force directions: Where is the direction of force? And What is the net force? I'm trying to calculate it using their angles, ...
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### Norm of summation of vectors

If we have a vector $\partial_v$ and we want o find its norm, we easily say (According to the given metric) that the norm of that vector is:$g^{vv}\partial_v\partial_v$. My question what if we have ...
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### Another condition of calculating work

Let's imagine that there is a box placed at the corner of a table, and I push it so that my applied force makes an angle of 30° from the table's surface. The box would move and, due to the effect ...
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### What is the work done said when angle between force and displacement>90 and <180?

If the angle between $Force$ and $Displacement$ is obtuse then by using the formula of $Work$ we get negative quantity so is it said then that the system is losing energy or it is merely for the case ...
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### Infinite dimensional vector spaces vs. the dual space

I just happened across this over on Math Overflow. It references the following theorem from linear algebra: A vector space has the same dimension as its dual if and only if it is finite ...
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### How can kinetic energy be conserved in an elastic collision

How can kinetic energy be conserved in an elastic collision as collision is said to occur between two bodies if they physically collide against each other or if the path of one of then is affected by ...
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### How to calculate the horizon line of a satellite?

I need an equation to calculate a list of Earth-centered, Earth-fixed (ECEF) XYZ coordinates on the earth that represent the visibility limit of satellite given its ECEF XYZ coordinates. For any ...
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### Is velocity always tangential to trajectory?

So I was doing an exercise and they find find the angle between the tangential of trajectory and the vertical I was stuck but then I read in a site that the velocity is ALWAYS tangential to the ...
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### Torque on shaft

Consider a generator which supply power using a shaft to a turbine. The torque applied on shaft by generator is $T$. As the shaft has constant angular velocity the turbine should also be applying ...
Consider a particle in two dimensions with position vector $r(t)=<x(t),y(t)>$ and the shape of the path is described by a function $y(t)=f(x(t))$ (Thus $r(t)$ is a parametrization of $f$ with ...