What is Horizontal: Definition and 978 Discussions

The horizontal branch (HB) is a stage of stellar evolution that immediately follows the red-giant branch in stars whose masses are similar to the Sun's. Horizontal-branch stars are powered by helium fusion in the core (via the triple-alpha process) and by hydrogen fusion (via the CNO cycle) in a shell surrounding the core. The onset of core helium fusion at the tip of the red-giant branch causes substantial changes in stellar structure, resulting in an overall reduction in luminosity, some contraction of the stellar envelope, and the surface reaching higher temperatures.

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  1. L

    Horizontal Motion with Quadratic Drag

    Homework Statement Consider an object that is coasting horizontally (positive x direction) subject to a drag force f = -bv - cv^2 . Write down Newton's second law for this object and solve for v by separating variables. Sketc the behaviour of v as a function of t. Explain the time dependence...
  2. C

    Is 66° Below the Horizontal? Solve the Equation

    Homework Statement if a questions states that the angle of 66 degrees is below the horizontal is that the angle I put into the equation Homework Equations The Attempt at a Solution
  3. M

    Natural Convection - horizontal cylinder

    Nusselt number: 1) The only correlation I could find so far is the one described here http://en.wikipedia.org/wiki/Natural_convection which seems to be from Churchill/Thelen. There seem however to exist some questions regarding the characteristic length and the value to use for Nuo (see...
  4. L

    Projectile Motion- Horizontal Range and Time of Flight

    Homework Statement A rifle is used to fire two bullets. The first shot is at an angle of 60° above the horizontal and the second at an angle of 45° above the horizontal. The speed of EACH bullet as it leaves the rifle is 200ms^1. For EACH bullet calculate the horizontal range and the...
  5. J

    Question concerning work and horizontal force.

    Homework Statement If it takes a horizontal force of 300N to push a stalled automobile along a level road at a constant speed, how much qwork must you do to push this automobile a distance of 5.0m? Homework Equations W = F x \Deltax The Attempt at a Solution I used the...
  6. C

    Horizontal component of gravity on inclined plane

    I'm working on a problem in which a block sits on an inclined plane of angle @ above the horizontal. Assuming there is no friction, the block will slide down the plane with a force of mg*sin(@). The trouble I'm having is figuring out the horizontal and vertical components of that force...
  7. S

    Cannon & Cliff: Minimum Muzzle Velocity & Horizontal Flight

    a cannon located 60m from the base of a vertical 25m tall cliff, shoots a 15kg shall at 43 degrees above the horizontal toward the cliff (a) what must the minimum muzzle velocity be for the shell to clear the top of the cliff? (b) the ground at the top of the cliff is level, with a constant...
  8. H

    How Fast Will a Block Travel After Being Pulled on a Frictionless Surface?

    Homework Statement A 2.7 kg block initially at rest is pulled to the right along a horizontal, frictionless surface by a constant, horizontal force of 17.3 N. Find the speed of the block after it has moved 4 m. Answer in units of m/s. Homework Equations a=Fnet/mass The Attempt at...
  9. S

    Finding Horizontal Force Needed to Move an Object

    How can we find the horizontal force required to move an object with the coefficient of static friction and the mass?? I just need a formula please, thankyou
  10. H

    Convection over horizontal pipe in air

    I am working on a problem involving heat transfer from a horizontal pipe in air. I am having trouble with it and not getting the solution I expect, and I think it is because of the convection component of the heat transfer. The general formula I am following for convection from a horizontal pipe...
  11. D

    Tidal forces inside BH in horizontal direction

    Spaghettification outside of a BH rips apart objects in vertical direction, but compresses them in horizontal. Inside the BH, tidal forces rips objects apart in ALL directions - at least I was thinking so. But recently I read: http://arxiv1.library.cornell.edu/abs/0903.4717 The edge of...
  12. S

    Electric Fields of horizontal sheets

    Homework Statement Two very large horizontal sheets are 4.25 cm apart and carry equal but opposite uniform surface charge densities of magnitude \sigma. You want to use these sheets to hold stationary in the region between them an oil droplet of mass 364 \mug that carries an excess of five...
  13. S

    Toppling giving example of a block on horizontal surface?

    Please explain me the toppling giving example of a block on horizontal surface? Is friction necessary? What's its deal with center of gravity?
  14. R

    Calculating Flow Rate in Horizontal & Vertical Pipes

    Homework Statement A liquid is flowing through a horizontal pipe whose radius is 0.02m. The pipe bends staight upward through a height of 10.0m and joins another horizontal pipe whose radius is 0.04m. Homework Equations what volume flow rate will keep the pressures in the two horinontal...
  15. M

    Force Measurement Histogram: Vertical vs. Horizontal Axis

    I am a little confused about a histogram of force measurements. I was asked for my physics lab to state what the vertical axis and horizontal axis represent for a histogram of force measurements? the physics lab consists of pulling a wooden block with a force sensor to record the tension...
  16. X

    What is the Maximum Horizontal Distance for a Gazilcher Launch?

    Homework Statement Some students at Rice University have built their first gazilcher – a large slingshot (operated by five people at once, and capable of launching objects well over 100 meters in distance) constructed from surgical tubing and a cafeteria silverware basket. They wish to...
  17. T

    Horizontal Projectile Motion Problem

    Homework Statement A mountain climber jumps a crevasse by leaping horizontally with speed v_{o}. If the climber's direction of motion on landing is \Theta below the horizontal, what is the height difference h between the two sides of the crevasse? Homework Equations x=v_{o}t v_{x}=v_{o}...
  18. R

    Finding the area of a region between curve and horizontal axis

    Homework Statement Find the area under y = 6x3 - 2 for 5 <_ x <_ 10 Homework Equations The Attempt at a Solution I'm not sure how it wants us to do it; do we use sigma notation or the general right/left-hand sums? Using sigma notation, delta T = 10-5/n T0= 5/n (?) T1= 10/n Ti = 5i/n...
  19. S

    Ind a horizontal line y=k that divides the area* QUESTION*

    ind a horizontal line y=k that divides the area*URGENT QUESTION* Homework Statement Find a horizontal line y=k that divides the area between y=x^2 and y=9into two equal parts. Homework Equations integral b,a, ( f(x) -g(x) ) dx The Attempt at a Solution half of the total area...
  20. B

    What is the speed of the fluid when all of it is in the horizontal section?

    thanks
  21. B

    Horizontal component of projectile motion

    Unless there wind resistance do you always treat the horizontal velocity of a projectile as constant?
  22. Z

    What is the horizontal component of the force pushing him forward?

    Homework Statement An 80 kilogram skier slides on waxed skis along a horizontal surface of snow at constant veloctiy while pushing with his poles. what is the horizontal component of the force pushing him forward? [b]2. Homework Equations [/] is there an equation? The Attempt at a Solution...
  23. S

    Velocity in the horizontal and vertical direction

    Homework Statement Santa is in trouble. His reindeer just made a rough crosswind landing on the snow covered apex of this gingerbread house. Upon impact the hitch breaks free and the reindeer shoot skyward leaving Santa teetering on the very peak. As he slightly shifts the sleigh tilts...
  24. M

    What would be the effect on the results if the venturi meter was not horizontal and w

    What would be the effect on the results if the venturi meter was not horizontal and why? This is research i must complete before I carryout my experiment and lab report?? Help Plz
  25. G

    Finding the Magnitude of a Horizontal Force

    Homework Statement A 2.0 kg block on an incline at a 60 degree angle is held in equilibrium by a horizontal force. A) Determine the magnitude of this horizontal force (disregard friction) B) Determine the magnitude of the normal force on the block. I have no idea which equation to use...
  26. T

    Reasons why horizontal sync on LCD is erratic

    Hello,I recently found, yes found a DVD player headunit for a car in the desert. The touch portion of the screen, which was glass, was shattered, but the screen itself was intact. (More or less, save some scratches and the erosion of the matte finish in some areas) I have gone through the unit...
  27. I

    A 0.300 kg hollow sphere is rolling along a horizontal floor

    Homework Statement A 0.300 kg hollow sphere is rolling along a horizontal floor at 5.0 m/s when it comes to a 30 degree incline. How far up along the incline does it roll before reversing direction? Homework Equations Kinematics equations? The Attempt at a Solution I didn't...
  28. jegues

    Find Horizontal Range of Projectile with Initial Speed of 60m/s

    Homework Statement A projectile is launched with an intial speed of 60m/s. If it reaches a maximum height of 150m above this level surface then its horizontal range (in m) is ____ ? Homework Equations v^{2} = vo^{2} + 2ay y = yo + Vot + 1/2at^2 The Attempt at a Solution Vo =...
  29. B

    Find the vertical and horizontal asymptotes.

    Homework Statement Find the vertical and horizontal asymptotes. Homework Equations f(x) = earctan x The Attempt at a Solution Honestly, I am pretty stumped on this problem. I have graphed it on my calculator and messed around a bit, it seems that the horizontal asymptotes are around y =...
  30. H

    Oscillations on a horizontal.

    Homework Statement The two blocks in the figure oscillate on a frictionless surface with a period of 1.5 s. The upper block just begins to slip when the amplitude is increased to 36 cm. What is the coefficient of static friction between the two blocks? Homework Equations The...
  31. V

    Why is horizontal escape velocity less ?

    Homework Statement an asteriod with mass 6.6x10^17kg & radius 46km has escape velocity 44ms, but if the projectile is launched horizontally then the escape velocity is only 31ms, show that this is correct Homework Equations Vesc = SQRT (2GM/R) G = 6.67x10^-11 The Attempt at a...
  32. B

    Comparing Half Earths: Horizontal or Vertical Shadow Line?

    Sorry, I'm a newbie here and didn't know how to start a new thread, so I posted a question in another forum and then figured out how. I'm trying to redirect answers here. I'm arguing with a friend about how a half-Earth would appear from the Moon. Since we see the Moon in phases, it makes...
  33. G

    Timing a pendulum drawn back to the horizontal.

    Does this formula for the period of a pendulum work if the pendulum is drawn all the way back to the horizontal? Or does it only work when the angle off the vertical is small enough that its sine is approximately the angle itself? Note that my pendulum is stiff (a beam, not a weighted wire) so...
  34. T

    Why are Horizontal Axis Wind Turbines used other than Vertical Axis?

    Why are Horizontal Axis Wind Turbines used more often than vertical axis when it looks like a vertical axis has more of an advantage? Please can you explain it simply?
  35. D

    Work Done on Block Moving in Circle with Changing Radius

    Homework Statement A small block of mass 0.91 kg slides without friction on a horizontal table. Initially it moves in a circle of radius r0 = 0.63 m with a speed 1.5 m/s. It is held in its path by a string that passes through a small hole at the center of the circle. The string is then...
  36. H

    Finding magnitude of horizontal velocity

    Homework Statement A cannonball is launched horizontally from the top of a tall cliff with a horizontal speed of 45.0 m/s. The trajectory of the ball is shown in the diagram at the right. Determine the magnitude of the horizontal velocity and the vertical velocities of the cannonball after...
  37. N

    Block carrying a charge on a frictionless horizontal track

    Homework Statement A 4.00 kg block carrying a charge Q=50.0 µC is connected to a spring for which k=100N/m (see diagram). The block lies on a frictionless horizontal track, and the system is immersed in a uniform electric field of magnitude E = 5.00x10^5 V/m, directed as shown. If the block...
  38. F

    Horizontal velocity required to launch into orbit?

    At what horizontal velocity would a satellite have to be launched from the top of Mt. Everest (elevation 8848 m) to be placed in a circular orbit around Earth? I'm not sure where I'd start here, any tips?
  39. M

    Work required to accelerate a horizontal wheel

    Homework Statement How much work is required to accelerate a horizontal wheel of mass 1150 kg from rest to a rotational rate of 1 revolution in 5 seconds Homework Equations I = 1/2(m)(r^2) Rotational KE (ie work) = KE2 - KE1 Rotational KE = (1/2)(I)(Omega Squared) The Attempt at a...
  40. T

    Angular acceleration of a rod pivoted at an end, at angle below the horizontal

    Homework Statement The rod is at rest and is released, what is the angular acceleration immediately after release? The pivot is frictionless, gravity is 9.8 m/s^2. Homework Equations Icm = (1/12)ML^2 => Inertia at center of mass, this was given in the problem, i don't think it's necessary...
  41. M

    PROJECTILE MOTION - Given values are Horizontal & Verticle distance when time = 4s

    Homework Statement An object fired with a velocity of Vo covers a verticle distance of 20.0m and a horizontal distance of 25.0m in the 4th second of its motion. Determine the following: a) Its velocity of projection, Vo (the rest I am not going to worry about cos if i get part a) started...
  42. M

    Horizontal Circular Motion Problem

    Homework Statement A stopper is being twirled around(horizontal circular motion), that is attached to a pole with a string. What happens to the accuracy of Fnet = 4pi^2mrf^2(uniform circular motion equation) as the frequency of revolution of the stopper increases(assuming other variables of...
  43. S

    Calculating Tension in Horizontal Wire due to Magnetic Field

    Homework Statement A wire CD (mass = 50 g, length = 40 cm) is suspended horizontally by two vertical wires (both at 90 degrees /hanging straight down) which conduct a current I = 8.0 A. The magnetic field in the region is into the paper and has a magnitude 60 mT. Calculate the force on the...
  44. Z

    Speed of light vertical and horizontal in gravity

    The speed of light in a gravitational field is predicted to vary between the horizontal and the vertical. This prediction comes from the Schwarzschild solution. The vertical speed c = cof The horizontal speed c = coSQRT(f) Where f is 1-2GM/rc2 Because f is smaller than 1, the vertical...
  45. S

    Finding horizontal range from projectile.

    Homework Statement A shell is fired from the ground with an initial speed of 1670m/s at an initial angle of 51° to the horizontal (a) Neglecting air resistance, find the shell's horizontal range. (b) Find the amount of time the shell is in motion. Homework Equations dx=vi+.5at^2...
  46. D

    Ideal Projectile Motion , horizontal and vertical components?

    Homework Statement You throw a ball toward a wall with a speed of 32 m/s at an angle of 40.0° above the horizontal directly toward a wall. The wall is 22.0 m from the release point of the ball. (a) How far above the release point does the ball hit the wall? (b) What are the...
  47. C

    What is the time it takes for a player to come to a stop from sliding?

    Homework Statement A person slides to third base. The coefficient of kinetic friction between player and the ground is 0.70. His velocity at the start of the slide is 8.23m/s [forward]. Prove that the time it takes the player to come to a stop from sliding is: time = initial velocity divided...
  48. D

    Ideal Projectile Motion , horizontal and vertical components

    Homework Statement You throw a ball toward a wall with a speed of 32 m/s at an angle of 40.0° above the horizontal directly toward a wall (Fig. 5-33). The wall is 22.0 m from the release point of the ball. (a) How far above the release point does the ball hit the wall? not sure what...
  49. M

    Solving a Differential Equation for Horizontal & Vertical Motion

    Hello, this was a topic we were discussing in class, but its not mandatory to solve and not for credit so hopefully it's ok to post here: So take a horizontal block of mass M on a spring with length L. If coordinate system is x is positive to the right and spring and block are to the right...
  50. A

    Finding Horizontal Distance in Projectile Motion

    Homework Statement A 0.5kg rock is projected from the edge of the top of a building with an initial velocity of 13.7m/s at an angle 60o above the horizontal. The building is 6.89m in height . At what horizontal distance, x, from the base of the building will the rick strike the ground? Assume...
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