Magnitude and direction Definition and 202 Threads

Absolute magnitude (M) is a measure of the luminosity of a celestial object, on an inverse logarithmic astronomical magnitude scale. An object's absolute magnitude is defined to be equal to the apparent magnitude that the object would have if it were viewed from a distance of exactly 10 parsecs (32.6 light-years), without extinction (or dimming) of its light due to absorption by interstellar matter and cosmic dust. By hypothetically placing all objects at a standard reference distance from the observer, their luminosities can be directly compared among each other on a magnitude scale.
As with all astronomical magnitudes, the absolute magnitude can be specified for different wavelength ranges corresponding to specified filter bands or passbands; for stars a commonly quoted absolute magnitude is the absolute visual magnitude, which uses the visual (V) band of the spectrum (in the UBV photometric system). Absolute magnitudes are denoted by a capital M, with a subscript representing the filter band used for measurement, such as MV for absolute magnitude in the V band.
The more luminous an object, the smaller the numerical value of its absolute magnitude. A difference of 5 magnitudes between the absolute magnitudes of two objects corresponds to a ratio of 100 in their luminosities, and a difference of n magnitudes in absolute magnitude corresponds to a luminosity ratio of 100n/5. For example, a star of absolute magnitude MV=3.0 would be 100 times as luminous as a star of absolute magnitude MV=8.0 as measured in the V filter band. The Sun has absolute magnitude MV=+4.83. Highly luminous objects can have negative absolute magnitudes: for example, the Milky Way galaxy has an absolute B magnitude of about −20.8.An object's absolute bolometric magnitude (Mbol) represents its total luminosity over all wavelengths, rather than in a single filter band, as expressed on a logarithmic magnitude scale. To convert from an absolute magnitude in a specific filter band to absolute bolometric magnitude, a bolometric correction (BC) is applied.For Solar System bodies that shine in reflected light, a different definition of absolute magnitude (H) is used, based on a standard reference distance of one astronomical unit.

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  1. B

    Magnitude and direction of the current in conductor

    I have a few questions on three circuits problems that I have already solved. I explained how I arrived at my answers and included diagrams. I would appreciate any help in confirming that my answers are correct. Thank you! 1. The diagram below shows electric currents in conductors that meet...
  2. I

    Electrostatics - Magnitude and direction of electric force

    Homework Statement What are the magnitude and direction of the electric force on the +2.0x10^-6 charge shown in the diagram (included in the attachment)? Homework Equations F = kq1q2/r^2 The Attempt at a Solution I used the Ep = kq1q2/r^2 equation and plugged in the numbers but...
  3. C

    Magnitude and direction of the force of the seat on you?

    Homework Statement One fine spring day you decide to skip class and go to the amusement park to ride the loopthe- loop roller coaster. At the bottom of the loop, you’re moving with a speed of 20 m/s in a vertical circle 20 m in diameter. What’s the magnitude and direction of the force of the...
  4. S

    Derive the magnitude and direction of the linear acceleration

    [Solved] Centripetal Acceleration Homework Statement Derive the magnitude and direction of the linear acceleration at the tip of the stick, ignore the effect of gravity. Homework Equations r = length of stick a = dv/dt The Attempt at a Solution I first find the x and y components...
  5. C

    Magnitude and Direction of Puck on Ice

    Homework Statement A 0.170 kg puck rests on frictionless ice. Two hockey players strike the puck simultaneously. #1 force is 350. N exerted at 020.0T, and the other #2 force is 600. N exerted at 065.0T. What is the magnitude and direction of the puck's acceleration at the instant that it is...
  6. C

    Magnitude and direction of the force on the electron

    Homework Statement An electron is moving in a quadratic potential of the form V(x)=k(x-x0)^2, where k=10V/m^2 and x0=5m. x is positive to the right and negative to the left. Find the Following A. Find the magnitude and direction of the force on the electron at x = 0m B. Find the...
  7. C

    Magnitude and Direction of Force

    Homework Statement http://img243.imageshack.us/my.php?image=61581222vi0.jpg http://xs433.xs.to/xs433/08440/untitled601.jpg I need to find the direction and the magnitude of F3 given only the figure and the resultant force of the 3 vectors =20 lb, plus F3 being the smallest force between...
  8. S

    Magnitude and Direction of Electric Field at the origin? Please help

    Homework Statement A continuous line of charge lies along the x axis, extending from x=+xo to positive infinity. The line carries charge with a uniform linear charge density lambda. What are the magnitude and direction of the electric field at the origin? Homework Equations E =...
  9. R

    How Do You Calculate Vector Components in Physics?

    http://img45.imageshack.us/img45/7585/physicspz0.th.jpg Well I really have no idea where to begin with this one, if anyone could get me pointed in the right direction that would be much appreciated.
  10. M

    Magnitude and direction of the resultant.

    Question: i have 2 arrows/vector. One going down 13m and one going up 3m. it ask what is the magnitude and direction. Direction should be south and north. But how do i find the magnitude? and what is that? is it: -13 + 3 = -10m?
  11. T

    Electric Force magnitude and direction

    Homework Statement Three charges are arranged as shown in the picture above. Find the magnitude and direction of the electrostatic force on the 6 nC charge. The direction I am looking for is the angle that the resultant force makes with the positive x-axis. Do not include units for the...
  12. A

    Finding magnitude and direction of resultant force

    Homework Statement A rocket fires two engines simultaneously. One produces a thrust of 725 N directly forward, while the other gives a 513-N thrust at 32.4° above the forward direction. Find the magnitude and direction (relative to the forward direction) of the resultant force that these...
  13. B

    Magnitude and direction of acceleration

    1. You are going toward home plate at speed of 5.9 m/s when you hit the dirt. You slide for 1.1 s just reaching the plate as you stop. a)What is the magnitude and direction of your acceleration? b) How far did you slide?I got 5.36 m/s^2 for the acceleration. Not sure if I did this right.
  14. B

    Magnitude and direction of acceleration

    Homework Statement An aircraft in level flight at a speed 210ms^-1 and traveling due north turns 14 degrees east. If the manoeuvre takes 1.2s to complete what are the magnitude and direction of the acceleration? Homework Equations a = v/t magnitude = (sqrt)x^2 +y^2 The...
  15. N

    Finding the Magnitude and Direction of Force one with the Resultant Given

    Homework Statement Determine the magnitude and direction theata of F1 so that the resultant force is directed vertically upward and has a magnitude of 800N. Homework Equations The Attempt at a Solution I have difficulty of where to start the problem? do i sum up the forces of...
  16. S

    Calculate the magnitude and direction of the electric field

    Homework Statement [1] Sphere A has a radius of 10.0 cm and carries a charge of +5.0 x 10^(-8) C while sphere B has a radius of 5.0 cm and carries a charge of -2.0 x 10^(-8) C. The spheres are conducting hollow, and concetric. A) calculate the magnitude and direction of the electric...
  17. T

    What is the magnitude and direction of vector c

    Homework Statement Vector A points to the right with magnitude 10 m/s, and vector B points upward vertically with magnitute of 15 m/s. What is the magnitude and direction of vector c such that A+B+C=0 Any ideas on this problem are appreciated.. Homework Equations The Attempt...
  18. C

    Find magnitude and direction of these vectors

    Homework Statement Find the magnitude and direction for the vector A-B. Vector A=3m, Vector B=3m Homework Equations The Attempt at a Solution Wouldn't it just be 0? 3-3=0 Thank you very much
  19. C

    Magnitude and Direction of Electric Fields

    Homework Statement A small object A, electrically charged, creates an electric field. At a point P located 0.250m directly north of A, the field has a value of 40.0N/C directed to the south. A) 1.11×10^−9C B) −1.11×10^−9C C) 2.78×10^−10C D) −2.78×10^−10C E) 5.75×10^12C F)...
  20. H

    Net Torque magnitude and direction

    Homework Statement Three forces are applied to a wheel of radius 0.350m, as shown in the figure. One force is perpendicular to the rim, one is tangent to it, and the other one makes a 40.0 angle with the radius. a) What is the magnitude of the net torque on the wheel due to these...
  21. U

    Magnitude and Direction of Electric Field - Question

    I also have another question that I am very confused about Here it is I think you are suppose to find the magnitude and direction of the electric field and the formula needed is, E = 1 / (4x 3.14 x e0) x (density x distance / R^2) And I was told integration is needed too...
  22. K

    Displacement: Magnitude and Direction

    Homework Statement Jim walks 100m due south, 60m due east, and then 20m due north. What is his net displacement (both magnitude and direction)? Homework Equations I know how to find the net displacement by the magnitude of the distance... using the d = sq. rt ( (x2-x1)^2 + (y2-y1)^2...
  23. K

    How Do You Calculate Direction in Vector Displacement Problems?

    Displacement: Magnitude And Direction (urgent) Homework Statement Jim walks 100m due south, 60m due east, and then 20m due north. What is his net displacement (both magnitude and direction)? Homework Equations I know how to find the net displacement by the magnitude of the...
  24. E

    How Do You Calculate Net Force on Charges at Triangle Corners?

    Homework Statement Three charged particles are placed at the corners of an equilateral triangle of side 1.2m. The charges are +4 macroC, -8macroC and -6macroC. Calculate the magnitude and direction of the net force on each due to the other two...
  25. T

    Magnitude and direction of electric force (file attached)

    Homework Statement I was kind of confused on how the radius for the charge on q3 by q1 is 2a^2, i attached the file for my notes regarding this. The question is at the bottom of the pdf scan. Homework Equations The Attempt at a Solution
  26. L

    Find the magnitude and direction of the sum of momenta

    Homework Statement An 85 kg jogger is heading due east at a speed of 2.2 m/s. A 55 kg jogger is heading 20° north of east at a speed of 4.0 m/s. Find the magnitude and direction of the sum of momenta of the two joggers. Homework Equations The Impulse-Momentum Theorem The Attempt...
  27. S

    What is the magnitude and direction of the electric field

    What is the magnitude and direction of the electric field at a point midway between a -7.0 µC and a +6.0 µC charge 2.5 cm apart? Assume no other charges are nearby. I thought I was approaching the problem correctly, but I'm not getting the right answer. I used the equation: E = k(Q1 + Q2)/L^2
  28. B

    I NEED IMMEDIATE HELP for solving the magnitude and direction of current

    ok here's the prob. Two parallel wires are 20cm apart. EAch wire is 1.5 m long. The wire on the left carries 10 A of current up. Find the magnitude and direction of the current of the wire on the right ir it is REPELLED WITH A FORCE OF 10N. please help
  29. M

    Find the magnitude and direction of the electric force

    Homework Statement A particle has a charge of +1.5 µC and moves from point A to point B, a distance of 0.15 m. The particle experiences a constant electric force, and its motion is along the line of action of the force. The difference between the particle's electric potential energy at A and B...
  30. A

    Magnitude and Direction, Gravitational force Q

    I don't know if this is a very easy question or if I am totally missing something but the question is: What is the magnitude and direction of the gravitational force that acts on a women who weighs 500 N at the surface of the earth? From reading this, I am thinking that the magnitude would...
  31. P

    Magnitude and direction of velocity

    The end A of the link in a guide has a constant downward velocity of 3 m/s as shown in the diagram. For the instant where the link AB makes an angle of 75 degrees with the vertical guide calculate the magnitude and direction of the velocity of the roller at B, the magnitude and direction of...
  32. W

    Calculating Electric Field Magnitude and Direction

    Two point charges of magnitude +q and -q are placed on x-axis separated by distance d, as shown in the figure I provided (You can also look at the website I created). The point P together with the points where the two charges are placed forms an equilateral triangle. What are the direction and...
  33. P

    Magnitude and direction a uniform magnetic field

    magnetism Hi I'm stuck on this problem I its got to be something simple.Here goes... A proton moves perpendicularly to a uniform magnetic field B at 1.0x10^7 m/s and exhibits an acceleration of 2.0x10^13m/s^2 in the + x-direction when its velocity is in the + z-direction. Determine the...
  34. W

    Determine the magnitude and direction of the force problem

    I had a few questions which I'd appreciate some help with: Q3) A charge of 6 mC is placed at each corner of a square .100 m on a side. Determine the magnitude and direction of the force on each charge. I essentially found the force on one corner ( by using x and y components ) Hence, for X =...
  35. K

    Magnitude and direction of the resultant force

    1. Three ropes are tied to a box and three boys exert the following forces: F1=220 N @ 90 degrees F2=185 N @ 165 degrees F3=235 N @280 degrees Determine the magnitude and direction of the resultant force. For my solution I made a Vector Componant table, found the total force on the x...
  36. P

    Magnitude and direction of impulse

    I have a ball that is dropped from from rest at a height of 1.2 meters it hits the ground and bounces to a height of 0.7 meters. The mass of the ball is 0.5kg. I am assuming that initial velocity is 0 because it is released from rest. I need to find the magnitude of direction of the impulse of...
  37. C

    Calculating Wind Velocity: Solving for Magnitude and Direction

    I just can't figure out how to determine the magnitude and direction of the wind's velocity with this information, the combinasons of possibilities seem endless. An airplane traveling at a cruising velocity of 1000 km/h is headed south toward a destination of 1500 km away. In order to...
  38. T

    Interpreting Velocity Components in a Non-Head On Collision

    Hi all, I'm new here and am having a problem interpreting a homework question, hope i can explain it correctly. The question is below. "One ball goes along the x-axis and collides with a stationary ball of equal mass in a collision that is not head on. How does the y component of each...
  39. A

    Electric field - magnitude and direction

    I haev a homework problem where I need to find the magnitude and direction of the electric field from a thin, uniformly charged 18cm rod bent into a semicircle. The test point is at the center of the semicircle. It seems pretty basic but I am stuck on a point (assuming I am even on the right...
  40. N

    Calculating magnitude and direction

    Problem: A map suggests that Atlanta is 730 mi in a direction of 4.80° north of east from Dallas. The same map shows that Chicago is 562 miles in a direction of 20.9° west of north from Atlanta. Modeling the Earth as flat, use this information to find the displacement from Dallas to Chicago...
  41. J

    Airplane magnitude and direction

    Hi, The Question: An airplane is heading due south at a speed of 600km/h. If a wind begins blowing from the southwest at a speed of 100km/h (average), calculate: (a) the velocity(magnitude and direction) of the plane relative to the ground, and (b) how far from its intended position will...
  42. A

    Coulombs Law find the magnitude and direction ?

    We are dealing with Coulombs law or w/e in Physics right now AND I DONT GET IT lol In my homework. it gives numbers like +6.0 (weird u symbol)C and i jus don't understand how to find the magnitude and direction of everything.. Im a junior in Physics..so someone of higher...
  43. S

    Magnitude and Direction Problem

    These magnitude and direction problems always give me a really hard time! What other numbers should I have in order to solve this problem? Hopefully from that I will be able to figure out the proper equation to use. Thanks! Q: A roller coaster car of mass 320 kg (including passengers)...
  44. M

    Calculate the magnitude and direction physics

    ive been laboring over these two problems: A 4050 kg rocket is traveling in outer space with a velocity of 126 m/s toward the Sun. It needs to alter its course by 23.2°, which can be done by shooting its rockets briefly in a direction perpendicular to its original motion. If the rocket gases...
  45. P

    Magnitude and direction question

    "A sign weighting 495N is supported as shown in the attachment. Determine the magnitudes and directions of the forces exerted by the chain and by the bracket. assume that the horizontal rod cannot support vertical forces." How do I set up this question? Do I use the law of Sins? Cos? I...
  46. K

    Determine the magnitude and direction of the resultant force

    Three forces act simultaneously on point J. One force is 20.0 N north; the second is 20.0 N west; the third is 20.0 N 60° east of north. Determine the magnitude and direction of the resultant force. I need help with this problem. I know you can figure this out by putting it on a graph and...
  47. P

    Determine the magnitude and direction

    Determine the magnitude and direction of the effective value of g at a latitude of 33.0° on the Earth. Assume the Earth is a rotating sphere.
  48. F

    Magnitude and direction for the total gravitational force

    Please help me with the following problems! Four 9.5 kg spheres are located at the corners of a squareof side .60m. calculate the magnitude and direction fo the total gravitational force exerted on one sphere by the other three. *I think I'm supposed to use the forumula : F= G(m1)(m2)/r^2...
  49. F

    Calculating Resultant Force Magnitude and Direction Angle

    My problem is to determine the magnitude and direction of the resultant force FR=F1+F2 and it's direction, measured counterclockwise from the positive x direction. f1=250 lb @ 60 degrees from x f2= 375 lb @ -45 degrees from x Ok I got the magnitude by doing this: (360-2(255))/2=-75...
  50. F

    How Do You Calculate the Resultant Force and Its Direction from Two Vectors?

    My problem is to determine the magnitude and direction of the resultant force FR=F1+F2 and it's direction, measured counterclockwise from the positive x direction. f1=250 lb @ 60 degrees from x f2= 375 lb @ -45 degrees from x Ok I got the magnitude by doing this: (360-2(255))/2=-75...
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