Forces Definition and 1000 Threads

  1. AspiringPhysicist12

    Basic problem involving forces (Kleppner/Kolenkow)

    I attached my diagram/work done so far. I believe that as long as the angular velocity is always less than sqrt(2g), the object must fall downwards when it reaches the top of the drum wall. Also, the angular velocity cannot be greater than sqrt(2g), as ω=sqrt((g/r)cosθ) at all times, and can...
  2. P

    Forces at the bottom of a rotating U-tube filled with water

    So when the rotation starts some water will move upwards and in the vertical part of tube. I know hat centripetal force will be given by F=mv²/r Now I though of taking r as centre of mass of the water system but I don't know what to take the value of m as? Should I only consider the water...
  3. aspodkfpo

    Rock climbing with forces along a "cam clamp" axle

    https://www.asi.edu.au/wp-content/uploads/2016/10/Physics_ASOE2015solutions.pdf Q`12b) Unable to understand how they deduct the relation between Ffall and N via the angles. Unable to tell why this would act along the axle of the cam to the point of contact with the rod and be relatable to each...
  4. Like Tony Stark

    Conservative forces vs friction

    Hello I've written that homework statement as an example to illustrate my doubt: How can I tell if a force is conservative or not? I've read that, if the curl of the force is 0, it's conservative. But what about the friction force (##f=\mu N##)? Its curl is also zero, but it's not conservative...
  5. aspodkfpo

    What Is the Normal Force Acting On?

    If a box exerts a normal force on the floor, is this strictly on the floor or can we also regard the floor as the Earth?
  6. burian

    How to solve questions in pseudo force frames?

    $$ \frac{62 - .4mg + (.2) (m_{net} g)}{m} = a(t)$$ And, then I put ths into $$S=\frac{1}{2} at^2$$ But, my answer is not quite coming with what's in the options? So, my main confusions are, SHould the bottom most surface exert a force on the top most block, also where am I making mistakes...
  7. Vivek98phyboy

    What are the other forces acting on ##dm## in addition to gravity?

    After solving using energy conservation, I found the angular velocity at 37° to be omega=2.97/(L)^½ Tension and the weight (dm)g are the two forces acting on the tip dm To find the resultant force, I resolved the centripetal force and tangential force to find the centripetal force as F=...
  8. burian

    Two blocks on a third block which is split into two ramps

    So, for this question first I did a free body diagram in the perpendicular x-y axes, and, I got some equations with the normals, but the answer is independent of normal forces. So, I'm not sure how to eliminate the two normals. Further I find it quite weird that big block-A doesn't come into the...
  9. E

    Basic question about coplanar forces

    Summary:: Adult brand new to maths and physics and starting from the bottom, just for a hobby. I'm working my way through Schaum's Outline of College Physics and cannot understand why the N unit in the below table goes from 15.0N to 7.5N. Total beginner here, and help appreciated :) I have...
  10. M

    Motion when 2D forces are exerted on masses at each end of a baton?

    Let's say you have a simple structure with two equal masses connected by a massless rigid baton of length L. Like this: Imagine this structure is totally free in space. It is not hinged in any way. Then forces act on each mass in 2D (x,y). If you have the x and y force vectors acting on each...
  11. mcastillo356

    Verifying Coordinate System for Electric and Magnetic Forces

    The attached file is the coordinate system I've used a) $$\vec{E}=\dfrac{\vec{F_e}}{q}=\dfrac{1,10\cdot{10^{-13}}\hat{j}\;N}{1,6\cdot{10^{-19}}\;C}=6,88\cdot{10^5}\hat{j}\;N/C$$ b) $$\sum{\vec{F_{net}}}=\vec{0}=\vec{F_e}+\vec{F_m}$$...
  12. S

    B Action-Reaction forces and angles

    Now, I am sure we all know that objects and their action-reaction forces happen in terms of exerting forces at opposite directions but with the same magnitude. That said, I wish to ask: Do objects with action-reaction forces have their forces exerted in opposite angles as well as opposite...
  13. S

    I Forces (Fields) of Nature and Quantum Foundations

    Is it possible for new forces or fields of nature to be connected to quantum foundations? For example, new forces or fields that choose the decoherent histories or branches. Or generally actualize one of the decoherence branches? Or should new forces or fields of nature be reserved for...
  14. S

    B Question about Action-Reaction Forces

    I have a question about action-reaction forces, and it mostly has to do with contact action and reaction forces, but it can include action-at-a-distance forces, too. So, can there be multiple action-reaction forces on the same two objects, like a chair and the floor, for example? By multiple...
  15. Hiero

    I Distinguishing gravity from fictitious forces

    Is the above statement accurate? I am just wondering, aren’t tidal forces also produced by the centrifugal force of a rotating frame? So then what really distinguishes gravity from fictitious forces? (I don’t know any general relativity so if you reference things like the Riemann curvature...
  16. Jiman

    Is the principal of superposition of forces a part of the second law?

    The three laws are basic principles in Newtonian Mechanics. The principle of superposition of forces is part of the second law.But before we make the assumption of superposition of forces,we have to make another assumption which is the principal of superposition of motion.why are...
  17. Bob Walance

    B General Relativity & External Forces: 2 Cases Examined

    It seems that there are two distinct gravitational cases to consider: a) Object with no external contact with any type of stuff (e.g., a person in free-fall in a vacuum) b) Object WITH external contact (e.g., a person standing on the ground) I've enjoyed reading and listening to various...
  18. L

    I How Do Jacobi Fields Explain Tidal Forces in General Relativity?

    Given a one parameter family of geodesics, the variation vector field is a Jacobi field. Mathematically this means that the field, ##J##, satisfies the differential equation ## ∇_{V}∇_{V}J =- R(V,J,)V## where ##V## is the tangent vector field and ##R## is the curvature tensor and ##∇## is the...
  19. Ranku

    Electrostatic and gravitational forces

    An object on the surface of the ground does not penetrate the ground. How much is this because of the electrostatic force between the particles constituting the ground and the object, and thereby maintaining their integrity? And, how much is it because of the materiality of the mass of the...
  20. mingyz0403

    Engineering Moment of forces about the axes

    I reslove Ma and Mb into y and z component. Ma=1200sin(20)j+1200cos(20)k Mb=900sin(20)j+1200cos(20)k Mc=-840i I looked at the solution and it states that the y component of Ma is negative (-1200sin(20)j+1200cos(20)k). I understand that Mc is -840i because it is Clockwise. How do you determine...
  21. T

    Calculating Forces in a Pulling System: Fp, Wp, Wm

    Fp = Fg +Ff Fp = (21*9.81*sin(31)) + (0.2*21*9.81) Fp = 147.30 Fp*d = 147.3 *4.5 Wp = Wm = 662.87 = 663 J I am not sure what I am doing wrong. Should I subtract the force of friction from the force of gravity? Have I assumed that the pulling force is equal to the sum of gravity and friction...
  22. LCSphysicist

    Solving a Closed System w/Conservative Forces: Is E1=E2 Always True?

    This problem is very easy to solve considering that the two particles belong a closed system under action of conservatives force. My doubt is if it is possible to solve the problem by consider one particle by time, that is: Suppose that we know the particle m one is under gravitational force...
  23. jaumzaum

    I Strong and Weak Nuclear forces at long ranges

    A lot of articles I already read says the Strong and Weak Nuclear interactions have a very short range, the first one being ##10^{-15}m## and the second ##10^{-18}m##. My first question is how is this calculated? This leads me to 2 possibilities:$ 1. Both forces actually act with an infinite...
  24. P

    Direction of Frictional Forces on Balanced Force Objects

    What is the direction of the frictional forces especially when there are 2 forces acting on an object? (see attached Image)
  25. Boyles

    Internal forces acting on a dive system

    Hello please be aware that my understanding of physics is basic, but I want to learn - and I will if explained simply enough please. I looked on here and found the cube in space query from last year, and I just about understood it, but the scalars and vectors did throw me, so hopefully it will...
  26. I

    Forces acting on a support point after the system is released

    Summary:: What is the force N which acts on a support point at the moment just after system is released? [Thread moved from the technical forums, so no Homework Template is shown] A light bar with m1 and m2 masses (m1≠m2) at the ends placed on the support point (in the middle of the bar)...
  27. A

    A What are the forces acting on an air particle along a fluid streamline curve?

    What forces act at air particle at curved streamline, looking from inertial and non-inertial frame of reference? (show free body diagram)
  28. A

    Centrifugal forces don't exist in reality?

    We can often hear that centrifugal force don't exist in reality...Helicopter mi-26 can lift 56tons ,it has 8 blades,so each blade hold 7 tons of force! Do you know if you put 7tons at blade when blade is not rotating(static) ,bending moment will be way too much and blade will broke at root...
  29. T

    Understanding forces acting on a pipe bend when fluid is passing through

    Hello all I am trying to understand the forces that are acting on a pipe bend when a fluid is passing through it. I have been given the following diagram:- The bit i cannot get my head around is why does P2A2 point the way it does i.e. down towards the left shouldn't is point the opposite...
  30. lucas pentland

    Net forces on a boat (propulsion, water and air resistance)

    2500 N [south] + 3200 N [south] = 5700 N [south] 5700 N [south] - 6000 N [north] = 300[north]
  31. chucho11028

    Understanding the Third Law of Newton — How can the forces be equal?

    Hello guys, The third law says: "For every action, there is an equal and opposite reaction. The statement means that in every interaction, there is a pair of forces acting on the two interacting objects. The size of the forces on the first object equals the size of the force on the second...
  32. K

    How Do You Calculate Forces when The Lorentz Force Doesn't Seem to Apply?

    If the mu of the ferrite is high, as suggested, the B field on that section of wire is zero, and therefore there is no force on the wire. Instead there is a comparable force on the ferrite itself. But suppose you allow the ferrite to have different values of mu. If mu=1 the force is just...
  33. J

    Calculation of the forces and the work of these forces

    Like AT asked I post a new thread because it is a different example, here there is no friction and I use a needle and an elastic to have the forces. The circle moves in horizontal translation, the circle doesn't rotate around itself, the red wall rotates around A0, and A0 is fixed to the...
  34. B

    A Could the fields for the particles and forces have the same origin?

    I was watching this terrific lecture by David Tong and there was a section at the end from around 50:12 - 54:00 that I found particularly fascinating. I am very much a layman when it comes to these topics and my question may be silly, but what sort of ideas are there that state that all the...
  35. LCSphysicist

    Analyzing Forces in Circular Motion: Finding Equilibrium in a Spring System

    https://www.physicsforums.com/attachments/262043I got here, i think that the component y N will balance the mg force; the other componente of N will be divided in two, one to balance the force, and other to be the centripal result, but i don't know how relate to each other
  36. E

    B Clarification of coordinate fictitious forces

    I was reading through this Wikipedia article and stumbled across a section related to outlining the differences between "state-of-motion" fictitious forces and "coordinate" fictitious forces. I have no idea what the second category is supposed to be, and wondered whether someone could explain...
  37. A

    2 Exercises with Forces -- dogs pulling a sled

    Hello ! we have recently been given the exercice stated above, along with a diagram that i inserted as a picture.The problem i have with this exercice is that i am not quite sure whether my idea about how to do it was right. I was thinking about replacing the normal force (N) in the F= mu x N...
  38. J

    I Does direct interparticle action imply advanced inertial forces?

    In his Nobel lecture (https://www.nobelprize.org/prizes/physics/1965/feynman/lecture/) Richard Feynman states that by varying the Schwarzschild-Tetrode-Fokker direct interparticle action $$A=-\sum_i m_i\int\big(\mathbf{\dot X_i}\cdot\mathbf{\dot X_i}\big)^{1/2}d\alpha_i+\frac{1}{2}\sum_{i\ne...
  39. F

    Question About Rotational Forces when Lifting Weights

    Hello, apologies if this is the wrong forum to post this. I have a question related to fitness. When holding a barbell overhead, sometimes it can spin due to poor timing, flexibility, etc. However, I notice it is significantly harder to counter the barbell's spin when holding it with a narrow...
  40. E

    Is there anything more to forces than being mathematical machinery?

    Real forces arise between pairs of interacting bodies. For any given system, classical physics tells you how to compute the forces (i.e. Coulomb/Newton inverse square laws etc.) acting one body due to another body, and then also tells you how different parts of the system move under the action...
  41. D

    Not sure if I have the correct angle and mass for this sum of forces

    Balance the forces east-west: 3.5kg*sin45º + 4.2kg*cos30º - 4.8kg*sin30º - E*cosΘ = 0 E*cosΘ = 3.712 kg balance north-south: 2.8kg + 3.5kg*cos45º - 4.2kg*sin30º - 4.8kg*cos30º + E*sinΘ = 0 E*sinΘ = 0.982 EsinΘ / EcosΘ = 0.982 / 3.712 tanΘ = 0.2645 Θ = 14.8º ◄ E = 3.712kg / cos14.8º = 3.84...
  42. H

    Circular motion, friction and forces

    I am not really sure how to go about this. I have been sick for a couple of weeks and fallen behind a bit. Can anyone help me out please? Thank you
  43. Physics lover

    Value of frictional forces in a 3-block system

    So I started by checking the options.I substituted the value of friction in the equations I got by making free body diagrams.I got different value of Tensions.For 1 and 3 Tension came to be 38 N.For 2 Tension came out to be 42N and for 4 Tension came out to be 40 N. Now I think that I will take...
  44. Tiago Carita

    How to calculate forces involved in a small fall

    Hi Guys, first things first I’m Tiago -= Introduction to my Many questions =- I work as Inventor in several projects of small scale, doing mechanisms, 3d printing, or building them cutting, welding, using my Lathe or sending to laser cut, bending or (when lucky) sending to a local CNC, I design...
  45. P

    A ship stops suddenly - Forces acting on the cargo?

    A ship is traveling at constant speed, i.e. the engine exerts a force equal to the drag force acting on the ship (right?). A cargo box is standing on the deck of the ship and is secured with a rope to the mast (see pic). When the ship kills the engine, the drag will create a sudden change in...
  46. FailedPaper5712

    Does anyone know how to resolve forces in 3 directions?

    I know the direction of the displacement is: i+2j-k, but I do not know how to resolve in 3 dimensions. If anyone knows how to do this could they please help me. Thank you.
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