Direction Definition and 999 Threads

Homework Statement A 60 g particle is moving to the left at 20 m/s . How much net work must be done on the particle to cause it to move to the right at 40 m/s ? Homework Equations 1/2 mv^2 = KE, W = ΔE The Attempt at a Solution My initial method of solving this problem was to take the...

Would the direction of the Magnetic Flux Density vector B at the south side be towards the south pole like this? and is the direction for B correct for the other side? One more thing, how can magnetic flux density be a vector and have a direction when its sort of a density, I mean its over an...

if i have no velocity in one direction then there is no acceleration ? i deal with acceleration for sphere in fluid so i use spherical polar co ordinates (ρ,θ,Φ) i have no velocity in Φ then there is no acceleration in Φ direction ? i want to be sure

I attached problem. I got F1 = 2.7x10-8 and F2 = 8.3x10-9 sqrt(f1^2 +f2^2) = 2.818x10^-8 theta was inverse tan of f1/f2. got 72.8 please help :(

I am currently looking at setting up a particle, with energy 5keV, traveling along the [11bar2 0] direction in Zr but I am struggling to get my head around how to resolve the velocity into the 3 directions to make sure it travels along this specific crystal direction. Could anyone help point...

Homework Statement 4) Find the direction does the Coriolis force in the following case a) a jet going north over the equator; b) a rocket going up at the equator; c) a pendulum at the equator viewed from above (please give the rotational direction.) d) a rocket going up at the south pole...

Can someone please explain me the direction of static friction? I know kinetic friction is always going against the motion of an object but for static friction it depends.

Homework Statement why the moment 560sin30 (0.25) isn't in clockwise direction ? the horizontal component of the 560N force is directed to the left , causing the moment in clockwise direction, am i right ? I have made my sketch beside in the diagram ... Homework EquationsThe Attempt at a Solution

http://postimg.org/image/we3bnkyqn/ I know electric field points in direction in which the potential is decreasing. How does potential decrease in that direction? Here is what I think potential at point a is 10v and at point b it is 20v and direction of E points from b to a,hence electric field...

Homework Statement in figure b , based on the direction of moment of anticlockwise is positive , i can say that -Tcos20 (7 sin 30 ) is a clockwise moment , so that the tension of rope should be acted in upward direction , so that the horizontal component of the force acted to the left to...

Homework Statement for no 4 , why the reaction force also act downwards ? as far as i know roller can only support the surface perpendicular to it upwards ... but not downwards... for no 5 , why the recation force acts upward only ? why not also downards?Homework EquationsThe Attempt at a Solution

Hi, I need some help with a problem in my Classical Mechanics undergrad course. We were assigned a problem in which we were given a one dimentional potential (some sort of a parabola). We were asked to determine the velocity's direction at different point, and even though it is somewhat...

Homework Statement the metal rod is supported by another metal rod at one end . The metal rod is supported by another metal rod at the end. so , the direction of tension of metal rod is acted upward , right ?( this is the initial prediction) But , i was told that the tension that we get from...

Homework Statement why the recation of the force is acted to the right ? why not to the left ? how to determine it ? Homework EquationsThe Attempt at a Solution

Homework Statement Homework Equations P=ρgh The Attempt at a Solution I already have the solution. My question is simple. I can't understand how I define the direction of pressure in each "changing" point. I also have the solution if needed.

Homework Statement Which is the correct diagram for concurrent forces? The left or the right one ? Homework EquationsThe Attempt at a Solution

Homework Statement Let's say the metal rod is held by a cable and supported by a pin at the bottom, the reaction of thr cable is acted downwards... Why? Homework EquationsThe Attempt at a Solution

Homework Statement A car with a mass of 1.3x10^4kg is initially moving at 35 km/hr in a straight line when the car comes to a complete stop at 15m. What is the magnitude and direction of acceleration?b) the magnitude and direction of the breaking force c) thetime required to stop Homework...

Homework Statement how to determine the direction of tension ? why it acted in downward direction ? wy not in upward direction ? Homework EquationsThe Attempt at a Solution

Homework Statement why i figure b , the direction of FBD is in downward direction , whereas in a , its in upward directon Homework EquationsThe Attempt at a Solution

In the aeroplanes, the drag is in the opposite way of the direction of the aeroplane. My questions for wind turbine: 1) Why "wind speed" and "the drag on the blade" is in the same direction? Shouldn't be the opposite? 2) Are freestream velocity and the wind speed same thing? 3) Are the drag...

Homework Statement I managed to get Fy = 900N , Fx = 200N and FR= 922N , how to get the distance from A is 3.56m ? tetha= arc tan (922/200) = 77.5 degree Homework EquationsThe Attempt at a Solution

Homework Statement if the alpha is larger than 90 degree ( which means the resultant F is lean towards -x axis , then the angle between the Ax and the line from Ax to A will be less than 90 , am i right ? Homework EquationsThe Attempt at a Solution

One of the possible decay modes of the neutral kaon is ## K^0 \rightarrow \pi^+ + \pi^- ## The rest masses of the K0 and pion are 498 MeV/c2 and 135 MeV/c2, respectively. In 2-dimensions (xz-plane), if the kaon has an initial momentum of 2000 MeV/c in the z direction, what is the momentum of...

I have been trying to better understand the concept of a photon (I know...a thousand threads on this alone) and the direction that it propagates. I understand the time-varying field explanation for em waves, but here is where I break down. If an electric field extends in all directions...

Hi guys, I trying to understand one thing that I don't know where came from. To visualize the problem I will used the drawings from book. The question is for direction of Force Fb on drawing (b) and (a). I was always learned that friction is acting on direct opposite to motion. In drawing...

I still don't really get the concept of moments.. if moment is what makes things rotate, imagine this : ....... F (pushing down the stick) ===================(stick) A so : 1. the stick will rotate in a clockwise direction, 2. but the direction of the moment is negative Z.. (right hand rule)...

1. Plot Px in horizontal direction about three quarters of cylndrical surface ABCD Px: horizontal force in unit length 2. formula: P=ρgh3. my question: ①Why does Px point at the right? ③What does the blank mean? Because ABCD is only 3/4 of a circle...

I read in radio astronomy book that radiation from high-energy electrons radiating synchrotron emision, is concentrated in the direction of its instantaneous motion. So if we see them, their orbital motion plane contains us(as observer). I am wondering if they have spiral motion in the related...

Hi everyone, I am wondering if anybody could help me out. For my study I got the following question but I got stuck in part C (see image below). I Found at A that due to symmetry all components which are not in Ar direction will get canceled out I found at B that there is only charge density at...

Homework Statement Homework Equations Total electric field = Electric field caused by Q_1 + electric field caused by Q_2 ##\vec{e} = \vec{e_1}+\vec{e_2}## Dipole moment = ##P = Ql## The Attempt at a Solution **For Part A** ##\vec{E} = \vec{E_1}+\vec{E_2}## The charges are opposite so it...

Homework Statement Calculate the direction of the electric field. There are four charges, each is at the corner of a square. One of the charges is -39 and the others are -27.7. Homework Equations The Attempt at a Solution I already got the right answer, but I don't understand the wording...

Homework Statement The drawing shows two cars traveling in different directions with different speeds. Their velocities are: vAG = velocity of car A relative to the Ground = 27.0 m/s, due east vBG = velocity of car B relative to the Ground = 21.0 m/s, due north The driver of car B looks out...

Homework Statement A 0.35 kg particle moves in an xy plane according to x(t) = - 11 + 1 t - 6 t3 and y(t) = 19 + 3 t - 8 t2, with x and y in meters and t in seconds. At t = 0.7 s, what are (a) the magnitude and (b) the angle (within (-180°, 180°] interval relative to the positive direction of...

Homework Statement A particle is moving along the x axis. Its velocity as a function of time is given by v = 5+10t , where v is in m/s. The position of the particle at t = 0 sec is 20 m. Find (a) the acceleration as a function of time (b)the position as a function of time (c) the velocity of...

Homework Statement Why shouldn't the direction of moment for 1200n at A =clockwise? Why the book gave counterclockwise? Homework EquationsThe Attempt at a Solution

Homework Statement IMO , the M2 and M1 should rotate clockwise, and the moment should point downwards based on right hand grip rule . Why the book gave in in other way ? Homework EquationsThe Attempt at a Solution

Homework Statement for the 400cos45 force , i think it should rotate anticlockwise, am i right? but the book gave it is rotated counterclockwise... Homework EquationsThe Attempt at a Solution

Homework Statement IMO, the direction of moment of both F1 and F2 should point inside the paper , and rotate clockwise , am i right ? but the book gave different things... which is correct? Homework EquationsThe Attempt at a Solution

So I have 2 questions to answer for my physics class and I'm not quite sure what to do. Here are the two questions and I was wondering if someone could possibly point me in the right direction. I'm not asking for the answers I just kind of want a rough idea of where to start. Thank you 1. An...

Homework Statement \Psi(y,t)=A\cos^22\pi(t-y) Show that this is a traveling wave. Use the general form of a traveling wave to determine its speed and direction. Verify your answer using \frac{-\partial \Psi / \partial t}{\partial \Psi / \partial x} Homework Equations The general form of a...

my questions are rather simple and stupid and i won't delve into theory like the last times how do we know the magnetic field lines are pointing inward on south and outward on north instead of inward on north and outward on south? or for this rule it's really the same question, how do we...

Homework Statement Find the magnitude and direction of the resultant of the following pair of forces: 60 N at 150 degrees to 20 N Answer: 43.8 N at 136.7 degrees to 20 N and 13.3 degrees to 60 N Homework Equations Cosine and sine rules: R2 = a2 + b2 - 2 * a * b * cos A a / sin A = b / sin b =...

A while back ( https://www.physicsforums.com/threads/direction-of-field-line-transforms-like-direction-of-a-stick.730373/ ), I posted a discussion here of the following seemingly mysterious relationship between two transformation rules: (1) If a field is purely electric in a particular frame...

I read this example in a book and I'm thinking about what is the "determining factor" of the directions of the magnetic field vector B and the magnetic force vectors F. If we start by looking at wire 1 in picture (a), if we only know the direction of the current (we call this "v"), can we...

Homework Statement Assuming positive x direction is counterclockwise, then why would the force 50n and 40n are turned clockwise ? (they have negative value) Homework EquationsThe Attempt at a Solution

Homework Statement To find the direction cosine of a equation say (4x+5y+7z=13) Homework Equations Im not really sure what to do The Attempt at a Solution (I know this is really basic but i would be glad if someone helps me with this

Homework Statement In this question, I didn't see why the given 90 degree is 90 degree becoz it doesn't look like 90 degree. Can someone draw me a better diagram? It's hard to visualize it's 90 degree Homework EquationsThe Attempt at a Solution

As we know all vectors with the same magnitude and direction are equal despite their different locations.so we can move the force vector such that Now how will it produce torque?Please tell me where am i getting wrong?

You and your little brother are rolling toy cars back and forth to each other across the floor. He is sitting at x = 0, and you are at x = 4.0 m. You roll a car toward him, giving it an initial speed of 2.2 m/s . It stops just as it reaches him in 3.0 s. In what direction is the car's...