What is Reaction forces: Definition and 64 Discussions

A rapid reaction force is a military or police unit designed to respond in very short time frames to emergencies. When used in reference to police forces such as SWAT teams, the time frame is minutes, while in military applications, such as with the use of paratroops or other commandos, the time frame is hours to days.
Rapid reaction forces are designed to intervene quickly as a spearhead to gain and hold ground in quickly unfolding combat or in rather low intensity conflicts, such as uprisings that necessitate the evacuation of foreign embassies. Because they are usually transported by air, such military units are usually lightly armed, but often extremely well trained to compensate for their limited to small arms and light crew-served weapons and the lack of vehicles, armor and heavy equipment like tanks.

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  1. A

    Engineering Problem with the reaction forces in the gearbox

    Greetings, I have tried to find the reactions of the bearings on the Y direction in the intermediate shaft. but I couldn´t find the numerical results of the solutions here is my attempt: in order to find the forces I did the moment equilibruim around the point A and B With FT1 FT2 and...
  2. H

    Calculating joint reaction forces

    I have this question in my biomechanics class, and the way the teacher has solved it raised some questions with me. This is the snippet of work from the lecture slides: But, if we see the red variables acting as 'placeholders' for the value of respective forces, and the value of the force at...
  3. S

    I Base Motion and Vertical Beam - Basic Reaction Forces?

    So I am trying to understand how to estimate the amount of deflection [D] the vertical beam shown above would experience if the base it is attached to is accelerating at a constant acceleration [a] of 9.81 m/s. I assume the Force [F] would be equal to weight of the vertical beam (mass x...
  4. D

    Calculating Support Reaction Forces using Method of Joints

    Summary:: The question requires us to determine the member forces using method of joints but I couldn’t figure out how to calculate the support reaction forces I tried to use equilibrium equations to solve the question but the force applied will be canceled out, and eventually the reaction...
  5. A

    Engineering Calculation of the reaction forces on a welded joint

    Here is my solution I just need it to be confirmed Many thanks in advance!
  6. L

    Engineering Find the reaction forces of shaft AB

    Given: r1 = 0.75 r2 = 1.5 Ok, i have done statics and dynamics, but this book does things differently than the way i accomplished it in the previous classes. This is for mechanical engineering design class. Here is my question. They take sum of the moments along X, which goes through the center...
  7. Like Tony Stark

    Reaction forces on a gyroscope

    I know that ##\vec{v_c}=(\omega_1;-\omega_2;0)×(L;-r;0)=0## So ##\omega_2=\frac{r\omega_1}{L}## Then, using the system of coordinates shown in the picture and ##\Sigma M_z## I can find the reaction force in ##C##. But how can I find the reaction forces on ##A## and ##O##? I mean, what system...
  8. A

    Statically Indeterminate Truck - Finding reaction forces at supports

    If you do the sum of vertical forces and sum of moments, you're always left with an unknown. Vertical Forces: Ray + Rby + Rcy = 59kN + 45kN (1) Sum of Moments about A: (59 x 1.85) - (Rby x 3.7) - (Rcy x 4.8) + (45 x 6.5) = 0...
  9. J

    Calculating Horizontal Reaction Forces in L-Beam

    Hi everyone, I'm new here so I hope I'm posting this in the right place. I'm struggling to duplicate the horizontal reaction forces being generated in an L shaped beam. Typically I like to do hand calculations and verify my answer using Solidworks, but in this case I can't seem to wrap my head...
  10. C

    Modeling reaction forces on a foundation for fences

    Hello new to the forum. I'm a builder by trade and enjoy studying the concepts behind the things I build. My problem is: A typical concrete post and base panel with a wooden fence. Unit mass approximately 350kgs including the foundation concrete around the posts. 2.0m wide x 2.0m above...
  11. F

    How do I analyze a body with a 14 kip force at a point?

    Homework Statement Homework Equations Using dimensional plane in the vertical y and horizontal x. ##\Sigma##Fx = 0 ##\Sigma##Fy = 0 ##\Sigma##Mz = 0 The Attempt at a Solution I have detached the 2 members at B and analyze them both separately. The 14 kip force is throwing me off though...
  12. M_Abubakr

    How Are Reaction Forces Calculated in a Hinged Beam and Strut System?

    Homework Statement Consider beam “A-B” and strut “C-D” from Figure QA1. The beam “A-B” is hinged at point “A” and hinged with strut “C-D” at point “C”. It has an applied force of 8 kN applied at point B as shown in Figure QA1. Strut “C-D” is hinged at point “D” and it is also hinged with beam...
  13. D

    How Can You Solve Reaction Forces in Bearings Using Basic Calculations?

    Homework Statement The problem asks to find the reaction forces for each of the bearings. For such bearings, the reaction forces can be looked up in a textbook, but they just act perpendicular to the shaft. Homework Equations Sum of the forces and moments = 0. The Attempt at a Solution I...
  14. F

    Understanding Reaction Forces: Problem 6.8 & 6.82

    I am having trouble recognizing reaction forces. for example, problem 6.8 on pin C there is no y component, the argument there was because there is no vertical member attached to C. That is understandable, but if we follow the same logic then there should not be an x component on pin A in...
  15. Epoch

    Calculating Reaction Forces on Cylinders Resting on an L Profile

    Homework Statement Two cylinders, each with a mass of 10kg, are lying on an L profile. Neglect the thickness and weight of the L profile. Calculate the reaction force in b and e. Homework Equations G = mg The Attempt at a Solution So I tried to make a free body diagram of the cylinders. I...
  16. C

    Solving for the internal forces and reactions

    Homework Statement I'm having a hard time finding the reactions at the supports and the force exerted by the spring. Given: 20 lbs 25 lbs 35 lbs k = 200 lb/ft lo = 2.5 ft members are 4 ft longHomework Equations ΣM ∑Fy = 0 ∑Fx = 0 The Attempt at a Solution I tried solving for the reactions...
  17. R

    Finding Forces in Member AE & AB: Exam Follow-up

    Homework Statement Determine all member forces and state if they are in tension or compression, in particular I am looking for member AE and AB[/B] Homework EquationsThe Attempt at a Solution Ok so we are supposed to redo the problems from our exam, only I can't figure out how to find the...
  18. T

    I Nozzle Reaction Forces: Explaining the Resultant Force

    I have been reading many examples of control volume calculations regarding nozzles They all end up with a reaction force on the nozzle in the direction of the flow. I can't understand this from a Conservation of momentum perspective. I would expect that the reaction force, by Newtons third...
  19. C

    Having trouble calculating reaction forces for this truss.

    Homework Statement Calculate reaction forces for truss. Truss is attached in picture. Homework Equations ΣFx=o ΣFy=0 ΣM about reaction point=0 The Attempt at a Solution attached in picture
  20. J

    Need Conceptual Framework for Reaction vs. Net Force

    I find the common physics problem of accelerating boxes that are touching very confusing. (To be clear, boxes are on surface, force comes from one side and all boxes accelerate. Questions typically ask about magnitude of force between particular boxes). Once the boxes are accelerating, why is...
  21. Y

    Reaction forces in a two segment beam

    Homework Statement Homework Equations ∑Fx=0 ∑Fy=0 ∑M=0 The Attempt at a Solution [/B] I am just concerned with part a. I got the correct answers doing this: First, FBD of segment AB: +cw ∑M_A=0: -136 - 6*By = 0 By = -22.7N two ways to get Ay: one: +cw ∑M_B=0: -136 + 6*Ay = 0 Ay =...
  22. D

    Need help using Method of Members to find reaction forces

    Homework Statement Determine the components of the forces acting on each member of the pin-connected frame shown. (the frame shown is drawn as a free-body diagram in the image provided below (the top-most portion) and is correct) Homework Equations Equilibrium equations: ∑M=0 ∑Fx=0 ∑Fy=0 The...
  23. mrtoodles

    Reaction forces in a pin jointed frame

    This is the question: http://i.imgur.com/Ex2Yx4l.png I have calculated all the angles in the frame, and have drawn line of forces so that the reaction force at x, reaction force at y, and the 10KN meet up. From then I am stuck, and don't know how to find the angle theta...
  24. I

    Calculating reaction forces on 3d object

    Hello all, I am in the process of calculating reaction forces on an object, and need some help. Attached is a free body diagram of an object in two different views- one looking from the sides (z-x plane) and one looking it in birds eye view. (xy plane) 7 variables I am looking to solve are...
  25. A

    Finding Reaction Forces on Pin Supports in a Static Equilibrium System

    Homework Statement I am given the forces on picture and I´m asked to find the reactions on both supports. I see they are pin supports so they ask me for 4 unknowns. Homework Equations Sum of forces in both directions equal to zero Sum of torques wrt a convenient point equal to zero THREE...
  26. J

    Reaction forces on simple 2 strut truss

    Homework Statement Calculate reaction forces R1x, R1y, R2x, R2y. Load of 100N. Node 1 and 2 are fixed. Distances listed on image. Homework Equations [/B] I have: ∑Fx = 0 = R1x + R2x ∑Fy = 100 = R1y + R2y ∑M2 = 0 = (-100 x 0.1) + R1 x 0.06 + R1y x 0.02 ∑M1 = 0 = (-100 x 0.04) + (-R2x x...
  27. J

    Statics problem involving moments and reaction forces

    Homework Statement The right angle boom which supports the 230-kg cylinder is supported by three cables and a ball-and-socket joint at O attached to the vertical x-y surface. Determine the reactions at O and the cable tensions. Homework Equations M [/B]= r x F unit vector =...
  28. hdp12

    Given Moment about a Pin and a Roller

    Homework Statement For my statics homework, we are directed to: Draw the free body diagram and use the force and moment equilibrium to determine the support reactions for the following systems I'm having a bunch of trouble with problem 4.10, which is displayed in the following picture I'm...
  29. B

    Reaction forces not matching with Test results

    Hello, I am analysing a 3D D shaped Incompressible Neo hookean material in contact with a semi cylinder using Ansys 14.5 APDL. The input values provided are C10=2737674.313898 and mass of D shape geometry to be 8 kg/m. I have converted these values into density and Shear Modulus as required in...
  30. M

    Determine the reaction forces at the supports

    Hello, so I've been given this question and I get a different anwser then my friends. Can you check if what I wrote is right? If its wrong then can you tell me what have I done wrong? Sorry for the quality of the picture but my Paint skills are not so great :) I was measuring to the right...
  31. A

    Reaction Forces on a Frame With Roller Joint and Pin Joint

    [b]1. Hi, The problem: A roof support frame has various leadings on it. The frictionless pin joint at points A has vertical and horizontal reaction forces. The rollers at point B allow free movement in the horizontal direction and has a vertical reaction. a/Calculate The total Horizontal...
  32. Z

    Reaction forces due to imbalance of a shaft

    Homework Statement The shaft carries two particles of mass m, and rotates about the z-axis with the constant angular velocity ##\omega##. Determine the x- and y-component of the bearing due to imbalance. The Attempt at a Solution Rotation only around the ##z-##axis so ##\omega _{x}=\omega...
  33. J

    Reaction forces in a Static system

    Homework Statement Rod AB is attached to a collar at A and rests against a roller at C. a = 107mm, l = 642mm, P = 110kN and Q = 30kN, determine: The reaction at A (by the vertical rod) (Unit: kN) The magnitude of the reaction at C (Unit: kN) Homework Equations This is my first...
  34. P

    What are the Corresponding Reaction Forces in a Suspended Bowling Ball System?

    Homework Statement A bowling ball is suspended from a ceiling hook using a thin piece of rope. If the rope is exerting a 65 N force upward on the ball, describe the corresponding reaction force in terms of: (a) its magnitude (b) its direction (c) on what object it is exerted (d)...
  35. M

    Structural Forces and Unknowns: Solving for Reaction Forces in a Complex System

    My problem here seems that I can't figure out how to solve for my unknowns. I have 3 equations for force, and I'm not sure if that equation I have for the moment around the origin counts as 3 new independent equations if I split them up into i, j, and k components. If that is allowed, then I...
  36. M

    Reaction forces on a structure

    Homework Statement Problem 4.36 http://xps2pdf.co.uk/4c82ad8dcb91d5507169e0a18804ea30bf81d592/4.36.pdf Homework Equations The Attempt at a Solution I am not sure if I am doing this correctly..there is a lot of information that I am not using to solve the problem (i.e. all the different...
  37. E

    Finding force load paths and reaction forces from ground

    I am looking to find the reaction forces on the bottom of the rectangular shape I have included (sorry for the crude diagram). I have a moment on the top right beam (390600 lb/in) and a distributed load of 160 lb/in across the entire surface of the top of the rectangular prism. I am looking...
  38. J

    Statics, beam attached to a wall, reaction forces

    Homework Statement I´ll show it with a picture: Homework Equations Static equilibrium, Sum Forces=0 ; Sum Moments= 0 The Attempt at a Solution With the Fx, and Fy equations I can calculate the reactions Rx and Ry but I don´t understand the moments equation: Sum M around...
  39. J

    Finding reaction forces for a Beam

    How do I find reaction for loading condition shown in image. I have no idea how to tackle this type of problem. Please help. http://img6.imageshack.us/img6/725/partilaudl.jpg Uploaded with ImageShack.us
  40. S

    Rod on a pivot: Linear acceleration and reaction forces

    Homework Statement Homework Equations r * \alpha = atan r * \omega^2 = arad The Attempt at a Solution arad = (L/2)(3g/L) = 3g/2 atan = (L/2)(3g/2L) = 3g/4
  41. B

    Action-Reaction Forces: Understanding the Basics

    This is not a question from a textbook, I am just supposing a situation. A book is lying on a table with some friction. If I push on the book, the book will push on me with an equal and opposite force; the book will then push on the table with friction, and, in return it, the table will push...
  42. F

    Action reaction forces: what is the reaction to tension?

    hello forum, consider an object attached to a rope and rotating in a horizontal loop. The tension T in the rope provides the centripetal force points toward the center of the loop. But forces always exist in pair (action-reaction). what is the other force in the pair where one of the...
  43. A

    Understanding Action & Reaction Forces

    I am kind of confused about this. What is the action and equal and opposite reaction?
  44. Hunus

    Regarding action reaction forces

    When I apply a force to a wall and the force applies a contrary force, what is causing the wall to apply this force on my hand on the atomic scale?
  45. Femme_physics

    Solving Tensions and Reaction Forces of Pole AB

    Homework Statement http://img101.imageshack.us/img101/9546/3dstats.jpg Pole AB is supported at point A by a pin joint, and held at point B by two wires, BC and BD, as described in the drawing. At point B acts on the pole force F which equals 500 [N]. The force F acts on a horizontal...
  46. N

    Reaction forces in simple beam involving applied moments

    Homework Statement Homework Equations The Attempt at a Solution The problem I'm having is that I'm not sure how to work out the reaction forces because of the applied moment of 50kN.m. I know that the formulas are the sum of forces in a single direction equals 0 and the sum of...
  47. A

    Do Multiple Reaction Forces Create Infinite Chains in Newton's Third Law?

    I have a 2 questions regarding Newton’s third law and I will explain them using examples: 1. Body A is pushing against Body B with a force F(AB), Now body B will push against body A with a reaction force F(BA) equal but opposite to F(AB). Now shouldn’t be another reaction force F2(AB) due to...
  48. E

    ANSYS Reaction Forces: How to Use for Calculating Bolt Forces

    Hello, Can the reaction forces at the mounting (fixed) holes of a component in a static structural analysis be used directly to find out the forces acting on the mounting bolts? If my understanding is correct, the force in the direction in the axis of the bolt will be used to find the...