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. M

    Isolating t in horizontal motion equation

    Isolating "t" in horizontal motion equation Homework Statement So this is just a practice question from my course and they gave me the answer, the problem I am having is understanding how they got to that answer. I have the formula and everything, just don't know how to isolate "t" and the...
  2. K

    Horizontal escape of a projectile

    Homework Statement The problem is attached Homework Equations L=mr^2(dr/dt) V_escape=(GM/R)^.5 E=L^2/(2mR^2)-(GMm)/R=0 The Attempt at a Solution after some work i got: dr/dtheta=((r^3/R)-r^2)^1/2 dont know what to do from here. Thanks.
  3. G

    Sketch graphs showing vertical & horizontal asymptotes and relative extrema

    Homework Statement Sketch the graphs of the following function showing vertical and horizontal asymptotes and relative extrema: f(x) = (x2-1)/(x2-4) Homework Equations Limits, zeroes, derivatives The Attempt at a Solution I know that I have the majority of the answers right, the...
  4. G

    Finding Horizontal Asymptote Process

    Homework Statement Find the horizontal asymptote of f(x) = (x2-1)/(x2-4) Homework Equations Limits The Attempt at a Solution I'm pretty family with the process, I just get confused when there's an x2 in the denominator and no x in the numerator ): So I already figured out that...
  5. M

    Find Acceleration of Blocks A & B | Homework Statement

    Homework Statement Question: 2 Blocks A and B are resting on a horizontal plane and connected by a cord as shown in figure. The Block A starts from rest and moves to the left with constant acceleration.It was observed that the Block B attains a velocity of 12 m/s after moving a distance...
  6. P

    Circular Motion of a horizontal disc Problem

    Hi :smile: A horizontal disc has a hole through its center. A string passes through the hole and connects a mass m on top of the disc to a bigger mass M that hangs below the disc. Initially, the smaller mass is rotating on the disc in a circle of radius r. What must the speed of m be such...
  7. C

    Can a horizontal bar exhibit SHM with rotating wheels?

    Homework Statement The Attempt at a Solution Please tell me how will there be an SHM?
  8. P

    Exploring Constant Friction with Horizontal Force

    Hello again, Sorry for posting two threads in one day. This is a general question. Suppose we have a box on a rough surface (fk). The box is being pulled by a horizontal rope(T1), and is moving with a constant speed v=0.5 m/s. Now suppose there's exactly similar situation but with...
  9. C

    Projectile Motion: Horizontal distance

    Homework Statement A jet flying at 250m/s at an angle of 20 degrees above the horizontal releases a bomb 200m above the ground, how far does the bomb travel horizontally before hitting the ground? Homework Equations vix = vicosthetha viy= visinthetha not sure what else... The...
  10. C

    Car traveling on horizontal road with force of static friction

    Homework Statement A car is traveling at 50 mi / hr on a horizontal highway a. If the coefficient of static friction between the road and tires on a rainy day is 0.100, what is the minimum distance in which the car will stop? b. What is the stopping distance when the surface is dry and μs =...
  11. Femme_physics

    Shouldn't this force have a horizontal component, too?

    In the solution manual (which I never trust) the tension vector of the rope that emerges from point A only has a vertical component when calculating the sum of all moments on joint C. I disagree with the solution manual, since this vector also has a horizontal component, and if you calculate its...
  12. E

    Solving for Horizontal Distance of an Arrow Shot Over Level Ground

    Homework Statement An archer shoots an arrow over level ground. The arrow leaves the bow at a height of 1.50 m with an initial velocity of 79.5 m/s in a horizontal direction. At what horizontal distance (in m) does this arrow strike the ground? The answer is 44m but I don't know how to get to...
  13. R

    Box Acceleration with Given Force and Coefficient of Friction

    Homework Statement A person is pushing a 15.0kg box on the ground with a force of 72.0N 65Degrees from the horizontal. if the coefficient of friction is0.12 what will be the acceleration of the box? Homework Equations Fnet=ma theres other formulas but i don't have my data sheet :(...
  14. R

    Determining Coefficient of Friction for a Sliding Toboggan on a Slope

    Homework Statement A 10.0kg toboggan is sliding down a hill with a slope of 15.0 degrees. If it is maintaining a constant velocity, what is the coefficent of friction? Homework Equations Fnet=ma Fg=mg Ffkinetic=mewFnormal i think Ffstatic=mewFN The Attempt at a Solution like I...
  15. K

    Coefficient of static friction and minimum horizontal force

    Homework Statement A 5.0 kg mass is held against a wall with which it has a coefficient of static friction of 0.85. What is the minimum horizontal force required to hold the mass against the wall ? The teacher said answer is 58 N .. i can't get to that answer.. Homework Equations...
  16. C

    Uniform Circular Motion in a Horizontal Plane

    Hey Guys. I am having issues with one of my physics homework questions, and i was seeking help. The question is as follows: While traveling around a roundabout, John notices that the fluffy dice suspended from his rear-vision mirror swing out. If John is traveling at 8m/s and the roundabout...
  17. D

    Airplane flying in a horizontal circle

    Homework Statement An airplane is flying in a horizontal circle at a speed of 410 km/h (Fig. 6-41). If its wings are tilted at angle a = 42° to the horizontal, what is the radius of the circle in which the plane is flying? Assume that the required force is provided entirely by an...
  18. A

    Trouble finding F(x) for a particle moving on a horizontal plane

    Homework Statement A particle of mass m moves along a frictionless, horizontal plane with a speed given by v(x)=k/x, where x is its distance from the origin and k is a positive constant. Find the force F(x) to which the particle is subject. Homework Equations F(x)=m\ddot{x}...
  19. M

    Why do simple balances always come to rest in a horizontal position ?

    Why is it that simple balances always come to rest in a horizontal position when equal weights are placed on both ends? If the weights are equal, then (assuming that the distance from each weight to the pivot is the same) the torques produced by the weights are equal and opposite and the net...
  20. H

    What Determines the Flow Speed in Differently Sized Horizontal Tubes?

    Homework Statement Seawater flows through a horizontal tube of diameter 3.00 cm that is joined to a second horizontal tube of diameter 1.70 cm. The pressure difference between the tubes is 7.25 kPa. What is the speed of flow in the first tube? Homework Equations I thought it was P1 +...
  21. C

    Calculating Work Done for a Box on Horizontal Floor

    Homework Statement A box, whose weight is 182 kg, is drawn with constant speed 21 m along a horizontal concrete floor. The kinetic friction between the box and the floor is 0.58. (acceleration due to gravity, g = 9,81 m/s2). Homework Equations Calculate the work done when the box is drawn...
  22. R

    A mass attached to two horizontal springs, vertical motion

    Homework Statement A mass is connected between two identical springs with the same spring constant, k. The equilibrium length of each spring is L, but they are stretched to 2L when the mass is in equilibrium. Ignoring gravity, find the equations of motion and then angular frequency of...
  23. H

    Object moving across horizontal plane.

    A wooden block is pulled across a level table by a horizontal force of 25N. If the coefficient of friction between the block and the table is 0.40 and the block is accelerating at 5.0m/s/s, what is the mass of the wooden block? I find Dynamics very hard and I just can't seem to figure it...
  24. M

    Solving Spring CD Horizontal Position Equilibrium Problem

    Homework Statement This is actually an engineering problem, but no-one ever seems to answer my questions when I post them there, and this is physics related. Spring CD remains in the horizontal position at all times due to the roller at D. If the spring is unstretched when θ= 0° and the...
  25. L

    Solving the Problem of Horizontal to Vertical Motion with Gear Design

    i am working on design of a machine which requires use of gear. I need to transmit horizontal rotational motion to vertical rotary motion. my question is their a means of getting the specific type and specification of gear am to use without calculating? if am to calculate how do i start and what...
  26. B

    Projective motion from a height, final velocity and horizontal distance

    Homework Statement A man stands on the roof of a 10.0 m -tall building and throws a rock with a velocity of magnitude 24.0 m/s at an angle of 30.0 degrees above the horizontal. You can ignore air resistance. Calculate the magnitude of the velocity of the rock just before it strikes the ground...
  27. C

    Object Slowing on a Horizontal Surface after Rolling down an Inclined Plane

    Homework Statement Block A starts from rest and slides 8m down a frictionless 30 degree angled inclined plane. It then crosses a 4m horizontal surface where the coefficient of kinetic friction is 0.2. What is the velocity of Block A after it has finished crossing the horizontal surface...
  28. H

    Cantilever beam with horizontal and vertical component point load at free end

    How do you calculate the stress in a cantilevered beam with a point load at the free end where the load has a large horizontal component loading the beam in tension as well as bending from the vertical component? And the beam bends far enough so it's slope will match the slope of the load at...
  29. H

    How do I find points on a curve where the tangent is horizontal?

    Homework Statement Find the points on the curve y=x3−x2−x+1 where the tangent is horizontal. I know that for it to be horizontal it needs a slope of 0 Homework Equations y = mx + b The Attempt at a Solution I don't have one, i can't think where to even start with this.
  30. L

    Horizontal Tangent Lines: Intersection of Cylinder and Plane

    Homework Statement Consider the plane z = x + 2y and the cylinder x^2 + y^2 = 1 (a) Find a vector function r(t) describing their intersection. (b) Find the points if any where the tangent to ~r is horizontal (c) Find an equation for the tangent line to ~r at each of these points.Homework...
  31. C

    Horizontal Recoil Speed of gun

    Homework Statement a 1200kg gun mounted on wheels shoots an 8kg projectile with a muzzle velocity of 600m/s at an angle of 30degrees above the horizontal. find the horizontal recoil speed of the gun Homework Equations KE= .5mvfE2 - .5MViE2 The Attempt at a Solution to be honest I...
  32. I

    Max horizontal distance wrt variable angle

    Homework Statement A ball is thrown with speed v from height h. What angle should it be thrown so it travels the maximum horizontal distance? I'll assume the angle theta is the angle from the horizontal to the initial direction of the velocity. Okay, since there is no air resistance we...
  33. A

    Finding Horizontal Speed of Electron in Electric Field

    Homework Statement So if an electron enters an electric field (between two charged parallel plates) at an angle (i.e not parallel to the x axis) and knowing that the speed is, say, 5 x 10^6 m/s, how would you find the HORIZONTAL velocity of the electron? you know that horizontaly it must...
  34. L

    How to Change a Horizontal Vector to Move in a 45 degree angle

    Homework Statement I am using vPython, and object moves in a +x direction with a vector of <1e7,0,0>m. I need to now change the vector so that it now moves in the same +x direction, but also moving in the northeast direction at an angle of 45 degrees. The Attempt at a Solution I...
  35. T

    Time dilation in horizontal clock

    hi, when talking about time dilation we base our idea(as i understand) such that; static observer relative to other one claims that lights' path is longer for him/her and since lights' speed is c for each of them time dilation occurs. This is quite obvious in vertical clocks but in horizontal...
  36. S

    Help me to understand horizontal component.

    what is horizontal component of Earth's magnetic field? BH. Please elaborate the concept. Thanks in advance.
  37. A

    Solving a Skier's Horizontal Distance Problem

    Homework Statement A skier starts from rest at the top of a hill that is inclined at 10.5degrees with the horizontal. The hillside is 200 m long, and the coefficient of friction between the skis is 0.075. At the bottom of the hill, the snow is level and the coefficient of friction is...
  38. M

    Rolling Ball on a Horizontal Bar with Angular Velocity ω

    bar (length L) is turned with angular velocity ω, on a horizontal level. Αt length of the bar, there is a ball (mass m) which rolls (We suppose that there is no friction force). The ball begins from constant utmost the bar with initial velocity u0. When the ball reaches in the L? Can you help...
  39. S

    Horizontal Forces exerted by door hinges

    Homework Statement A door of width 1.00 m and height 2.30 m weighs 272 N and is supported by two hinges, one 0.40 m from the top and the other 0.40 m from the bottom. Each hinge supports half the total weight of the door. Homework Equations Torque = rFsin(theta) The Attempt at a Solution I...
  40. R

    Angular Momentum Horizontal Metallic Bob

    Homework Statement A small metallic bob is suspended from the ceiling by a thread of negligible mass. The ball is then set in motion in a horizontal circle so that the thread describes a cone. Calculate the magnitude of the angular momentum of the bob about a vertical axisthrough the...
  41. W

    Constant horizontal pull on a sled

    Homework Statement A constant horizontal pull acts on a sled on a horizontal frictionless ice pond. The sled starts from rest. When the pull acts over a distance x, the sled acquires a speed v and a kinetic energy K. If the same pull instead acts over twice this distance, <the sled's speed will...
  42. M

    Points of Tangency for Horizontal Tangents in a Function

    Homework Statement Determine the points at which the graph of the function has a horizontal tangent f(x)=(x^2)/(x-1) Homework Equations The Attempt at a Solution f'(x)= ((x-1)(2x)-(x^2)(1))/((x-1)^2) ((2x^2)-2x-x^2))/(x-1)^2 f'(x)= ((x^2)-2x))/((x-1)^2) third step I set to 0 I...
  43. S

    The tension in the horizontal bar connecting the two halves of the ladder

    A stepladder of negligible weight is constructed where x = 1.80 m. A painter of mass 63.0 kg stands on the ladder 3.00 m from the bottom. Assuming the floor is frictionless, find the following. (Suggestion: Treat the ladder as a single object, but also each half of the ladder separately.)...
  44. J

    Is there a horizontal asymptote for y = 6/x - 3

    Homework Statement would there be a horizontal asymptote for y= 6/x - 3 Homework Equations I know that the vertical asymptote is x =3 because there the expression is undefined The Attempt at a Solution
  45. L

    Horizontal Spring-Mass Problem

    Homework Statement A 0.766-kg mass is attached to a horizontal spring with k = 78.0 N/m. The Mass slides across a frictionless surface. The spring is stretched 25.53 cm from equilibrium, and then the mass is released from rest. (a) Find the mechanical energy of the system. (b) Find the speed...
  46. I

    Probability of Hitting Vertical vs Horizontal Lines in 2D Grid

    Hi, I have a problem (1) where I need to compute the ratio of probabilities of hitting and stopping at a positive vertical barrier x vs hitting and stopping at a negative horizontal barrier y after starting from (0,0). I feel that by symmetry, the answer to this would be the same as...
  47. R

    Two Horizontal Forces Working On an Object

    Homework Statement Only two horizontal forces act on a 3.0 kg body that can move over a frictionless floor. One force is 9.0 N, acting due east, and the other is 9.4 N, acting 68° north of west. What is the magnitude of the body's acceleration? Homework Equations F=ma The Attempt at a...
  48. J

    Horizontal Pistons: Outside IC Engines?

    Can these work outside of an IC engine? The mechanism to move something left and right (Forward and back)
  49. F

    Help Polar, Horizontal Tangents.

    Homework Statement For the three leaf rose: r = sin(3\theta), find the co-ordinates of the five points where the tangent lines are horizontal. Interpret the significance of the five points. Homework Equations \frac{dy}{dx} = \frac{r'sin(\theta)+ rcos(\theta)}{r'cos(\theta) - rsin(\theta)}...
  50. N

    Finding horizontal tangents on an interval

    Homework Statement Determine all x in [-pi/2, pi/2] at which the graph has horizontal tangents. Homework Equations 1.) f'(x)= 9cos(x)-2sin(x) 2.) f'(x)= -5csc(x) (5cot(x)-csc(x)) The Attempt at a Solution 1.) 9cos(x)=2sin(x) 9/2=sin(x)/cos(x) 9/2=tan(x) and then I'm...
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