Forces Definition and 1000 Threads

  1. A

    Statics Question -- Analyzing the forces on this supported beam

    Can someone please tell me why I get two different result of the value of Cy (please see attached image for more detail)? Am I doing a mistake? If yes, what is my mistake?
  2. F

    Calculating Forces on a Moved Body

    I have a body moved by a crane hook and I want to represent the forces that act on the body in the case of translation, rotation and roto translation. Can someone help me? Thank you [Moderator's note: moved from a technical forum.]
  3. L

    Mass m sliding without friction inside a rotating tube

    1) To be in equilibrium, it must be $$\begin{cases}F_{centr}-T=0\\ T-mg=0\end{cases}\Rightarrow F_{centr}=T=mg\Rightarrow m\omega^2 R_0=mg\Rightarrow R_0=\frac{g}{\omega^2}$$ 2) It is intuitive that this equilibrium is unstable but I don't know how to formally prove this. 3) In ##R_0## the...
  4. A

    B Projectile motion — Thinking about forces on a curve ball

    When a ball is thrown such that it moves in a curved trajectory in the horizontal plane, it amuses me to think of its dynamics. In motion of a ball thrown upwards the force of gravity gives it a parabolic trajectory However when the ball is thrown to curve and hit a target, (in the horizontal...
  5. Shreya

    Is w Constant in Damped Oscillations?

    My first intuition is that for small damping Fd<<Fr
  6. B

    A Measuring new forces with molecular vibrations

    Hello! I noticed in several papers describing high resolution vibrational measurements in diatomic molecules, such as this one, in the conclusion section, that they mention that we can search for new forces (or deviation from gravity inverse square law) between the 2 nuclei by measuring well...
  7. jackiepollock

    B Problems regarding electrostatic forces in everyday levitation

    Hello! I'm reading this part of the A-level physics book and finding a few places that I couldn't wrap my head around. They are underlined. 1) When saying oxygen, is it saying that oxygen is the most abundant element in the shoe atoms? 2)I am not too sure why the force per atom is shared...
  8. L

    B Inertial Frame of Ref & Forces: Understand Special Relativity

    In trying to understand a bit of special relativity, I want to make sure if I understand it correctly, and I came up with the following question: "Imagine you would know all forces in the universe acting upon an object, doesn't that give away the only real existing frame of reference (imagining...
  9. Pratyeka

    B Do Gravitational Forces Increase for Objects Moving at Light Speed?

    Since an object's apparent mass increases as it approaches the speed of light, does it's gravitational forces also increases? (From a stationary observer's point of view)
  10. M

    A Moments and forces in different frames of reference

    Good morning! I know this may sound a little odd, because there is a theorem regarding it, but i have this question. Basically, a CFD analysis gives me the value of the forces and the moments, as a function of fuselage's orientation, in a particular frame of reference. How can i calculate the...
  11. almoga

    Statics - beam forces and moments

    Summary:: I did the first section but I am having a hard time with the second. would like to find the moment in the next section (from b to h)
  12. H

    I How do forces change with speed?

    Hey dear physics community :) I ask myself what exactly happens to forces between materia when the materia hits near lightspeed. I know, that for an objective bystander watching let's say elon in his rocket with 99,99999% the speed of light, that the time goes slower, the mass of the rocket...
  13. F

    Four fundamental forces of physics -- explanation for dummies please

    I am not sure if this is the correct place to post so I am very sorry if I am posting in the wrong place. I am looking to have the four fundamental forces of physics explained as simply as possible, I have been doing some online research to try to understand it and I am having a hard time...
  14. J

    Cam forces acting on a linear motion bearing with nonlinear forces

    I have a machine I am designing that for all intensive descriptions, is a simple press designed to compress loose product into a puck like shape. The press force comes from a roller bearing mounted to a piston shaft, the rod sliding through a rigid linear bearing and the piston on the end of...
  15. T

    Forces acting on a moving crane

    Can someone please help me understand where I am going wrong. I've checked my answer many times and do not understand what I am missing
  16. Richard Spiteri

    B Exploring Buoyancy: Investigating External Forces and Neutral Buoyancy in Water

    I am still intrigued by the neutral buoyancy of a body and have come up with some other questions. As previously encouraged, I attempted to answer my own questions (this is not home work, it is just me trying to wake up my brain in my retirement). Fig 1 has no question but builds on what...
  17. I

    Chemistry Intermolecular forces between NO particles

    The answer is dipole-dipole and London dispersion forces, but I only chose London dispersion forces. How would you determine whether there is a large or small electronegativity difference between N and O? And therefore how would you determine whether the N-O bond is polar covalent or non polar...
  18. M

    Should I consider internal forces for this hinged structure?

    Summary:: A hinged structure applied with a load, should the structure totally been calculated in order to find the resultant force? Hello, Two situations, the first is a simple structure with a 20 N load at point C. The moment-equation is composed next to it. Second situation: A hinged...
  19. M

    Tension and compression forces on a femur bone

    Summary:: Hello all, I need help with this question, ill attach the equations i managed to solve. How do i continue from there?
  20. R

    How to interpret the center of aero forces on a sports car?

    Hello. I am working on a physics project for a simulation title and have stumbled upon on an interesting challenge. Below is the example from wind tunnel data of a Dodge Viper GTS sports car. Wheelbase: 2,44m Lift front axle: 54kg Negative lift rear axle: 26kg Can somebody please explain to...
  21. S

    Hurricane forces — Comparing the force from a 60 mph wind to a 120 mph wind

    The marker wrote that the answer is 4 and it's because m and v double. I don't understand how m doubles??
  22. G

    Work done against resistive forces by comparing Ek and work done

    Missed units in the photo - J Answer is 110 000 J
  23. D

    Determine the forces using virtual work(unit force method)

    Summary:: Require to determine the designated forces using principle of virtual work ( unit force method ) I have no idea how to determine the multispan beam using virtual work, if I start to analyse the subsidiary portion BC member, the Yc can be calculated and following by the Ma... it seems...
  24. G

    I Are Tidal Forces Curvature of Space?

    I've heard it and I've read* it before, so I just want to make sure I understand this so I never have to wonder about it again. So, are tidal forces exactly curvature of space? Here's why I think the answer to that is yes: .I've seen a spacetime interval equation which has a coefficient on...
  25. 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...
  26. S

    Direction of forces on a uniform catilever

    The following is my work: The following is the answer given: While I took FA as the pivot point, the answer seem to have taken FB as the pivot point, and got negative value for FB. As the result, the answer seems to have used the tensile strength for FA and compressive strength for FB...
  27. GiriBang

    Resultant of two forces in two different situations

    https://cdn.discordapp.com/attachments/843776584255406080/847500756194033754/20210527_211342.jpg
  28. R

    The attractive gravitational forces between two people separated by 1.5 meters

    F= Gm1m2/r² = 1.667*10^-7 N. I don't understand How to calculate angular velocity?
  29. P

    Understanding the Forces Behind Part B of the Graph

    I am only asking about the answer to part B, but reading through part A may give some some context/familiarity. Below is the answer to part B: I largely understand the graph except for 1 part. My understanding is as such: At first, ##x = \frac {\mu_k m g } {k}##. Force exerted by the...
  30. shk

    Predicting Landing Point on a Moving Train: Exploring Forces and Motion

    I need help with the following question please. I understand that the person carries on in straight line while is jumping. This is because there is no horizontal force acting on him so based on Newton's first law of motion he continues with the previous speed. I know he should land on A or B...
  31. jacobtwilliams001

    Intermolecular forces and Transport phenomena

    I am able to find and understand T from kinetic theory, but I do not understand how to use pressure gradient per unit of area and per unit pressure gradient.
  32. S

    How do I calculate the ratio of forces between two conducting spheres?

    Here are the answer choices: a) F1 = 2F2 b) F1 = 8F2 c) 2F1 = F2 d) F1 = 4F2 e) F1 = F2 I figured that Coulomb's law would tell us the magnitude of the forces are identical, so I answered E, but that was incorrect. (Screenshot of question attached)
  33. simplemind

    I Question about particle interactions and the forces between them

    I have read that if the exchangeparticle of an interaction has even spin then the force between them is attractive if the charge is equal (gravitation) and repulsive if the charge is not equal. Is this wright?
  34. P

    I Fictitious forces and their associated energies

    I understand the idea of a fictitious force. What I am confused about is the energy/potential associated with it. For example, if a cylinder of water is rotating, there apparently exists this centrifugal potential energy, which is obtained by integrating mrw^2 dr. Why is it that the...
  35. B

    What are the forces exerted by a wall on a hinged rod?

    I have a dilemma. If I look at the diagram and say the sum of the forces in x and y direction has to be zero, then I will simply conclude that the force of a wall on a revolvable rod is the blue N as drawn. But what if the force is actually the green N? To me, it makes more sense because if...
  36. S

    MHB Forces of 8N: Find Angle & Mass of Particle

    Two forces each of size 8N, have a resultant of 13N. a) Find the angle between the forces b) The two given forces of magnitude 8N act on a particle of mass m kg, which remains at rest on a horizontal surface with no friction. The normal contact force between the surface and the particle has...
  37. rhotonsix

    What determines the direction of static friction forces?

    My understanding of static friction is that it is a resistive force in response to an applied force. I recently read the following example. A rope of uniform density, length L, is fastened to a plane with incline angle “theta” along its length. The question asks for the tension at the top of...
  38. Pipsqueakalchemist

    Engineering Questions on Forces & Friction: Analyzing Plate & Block Motion

    So I have questions on two separate questions. The first question is about the fbd of the plate attached to the pin. How can there be an Ax since there’s no other force in the horizontal direction wouldn’t the plate start moving on the x-direction due to imbalanced forces. Second question about...
  39. V

    Forces on particle in complex motion relative to ground observer

    A table with smooth horizontal surface is fixed in a cabin that rotates with a uniform angular velocity ω in a circular path of radius R. A smooth horizontal groove AB of length L(<<R) is made on the surface of the table. The groove makes an angle θ with the radius OA of the circle in which the...
  40. bo reddude

    I Physics of exercising and forces felt

    Let's imagine an ideal scenario where you're lifting your own weight in its entirety. Let's say a woman weighing 100 lbs. Suppose she's doing an idealized handstand and pushup from that position. So she's lifting 100 lbs. Let's say ideally all of the forces are on her arms only. Do these forces...
  41. P

    Meaning of F = -dU/dx for capacitors

    I have noticed that F = -dU/dx in gravitation gives the attractive force experienced by both bodies. For capacitors, does F = -dU/dx give the force experienced by each capacitor?
  42. P

    I Does the Normal contact force act through the centre of mass?

    Consider the following situation: You have 1 rectangular block lying on a table, and an identical block is placed above the block on the table. Now, this new block is constantly pushed to the right, right before it topples off. Consider the torque about an axis passing through the rightmost...
  43. P

    I Why is my derivation of the catenary wrong?

    Important note: I only derived the differential equation, I did not solve it. What I think caused the mistake: - the tangent approximation (tan(theta+dtheta) ~ tan theta + d theta
  44. K

    I Which forces maintain the shape of the Milky Way?

    Gravity, inertia, conservation of momentum and angular momentum are some of the forces and conserved quantities that I could think of which will tend to maintain the shape of the Milky Way. How is the separation of the spiral arms maintained?
  45. L

    Circular Motion Questions (energies, forces, angular velocities, etc.)

    Question 1: I believe that the ratio would be b. 8:1 because by combining the formula for kinetic energy and momentum the expression Ek=p^2/2m can be obtained. Thus, for a body of mass 2kg with twice the momentum: Ek=2^2/2*2=1 For a body of mass 4kg with half the momentum: Ek=1^2/2*4=1/8...
  46. I

    Find the distance x so that the two frictional forces are equal

    Letting the normal force on the pad on the left be 1 and the one on the right be 2, Normal force R1 + R2 = W Since the sled is not rotating, net moment =0, Taking moment about the right pad, W(ℓ/2 + x) - Hh - R1ℓ =0 R1 = W/2 + Wx/ℓ - Hh/ℓ Since the rate of the pads being worn is...
  47. J

    Forces on a crate with friction: find the normal force

    I have attempted this problem by solving for the normal force. (16.73)(9.8)-51.25(sin)(49.1). I tried to work that out but it was incorrect because apparently the vertical force is zero. Could I get an explanation on what that means and where I should start?
  48. A

    Sign convention of internal forces in vertical bars for bending moment

    Hello: I was looking for a widespread convention (akin to Hibbeler's, Beer's, etc) that deals with the sign convention of a vertical bar for bending moments. For example, without knowing in advance, how do I draw the bending moment at a cut passing through point E in the figure attached? Beam...
  49. 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!
  50. G

    To prove that three forces are in equilibrium

    Could I please ask for help regarding the following question: D, E and F are the midpoints of the sides QR, RP and PQ respectively of triangle PQR whose circumcenter is O. Forces of magnitude kQR, kRP and kPQ act at O in directions ##\overrightarrow{OD}##, ##\overrightarrow{OE}## and...
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