Force Definition and 1000 Threads

  1. G

    How to find the equilibrium position of three masses (two of them fixed)?

    Question: Suppose that two bodies of masses m1 and m2 are a fixed distance d apart, and that both of them act on a third body of mass m. Find the position of the third body such that the two forces are in equilibrium. I have solved this question and obtained the answer listed in the back of the...
  2. E

    Work done pushing a spring from the side

    My question is whether I've formed the integral for the work done correctly? It just seems a bit unwieldy to me... If I call the extension of the spring ## x ##, I can see that ## z = \frac l 2 + x ## and ## z^2 = \left( \frac {l} {2} \right)^2 + y^2 ##. Combining them gives: $$ x = \sqrt {y^2...
  3. mangofan

    I Electrostatic force exerted on an electron inside a nucleus

    This is SAMPLE PROBLEM 25-7 from "Physics" by Resnik, Halliday, and Krane, in the chapter "Electric Field and Coulomb's Law". After describing the behavior of uniformly charged spherical shells: follows a sample problem: The solution to (a) goes to say that the volume inside R/2 is 1/8 of the...
  4. ARoyC

    Total Force on a Point Charge in Motion

    As the observer is moving, there will be a magnetic force. Electric Field of the Rod = λ/2πεr r̂ Electric Force on the Point Charge = qλ/2πεr r̂ Magnetic Force on the Point Charge = q(vxB) = qvB n̂ = qv(µI/2πr) n̂ = qv(µλv/2πr) n̂ = µqλv²/2πr n̂ Total Force = Electric Force + Magnetic Force
  5. gkg

    A Force Changing With Distance (bead moving on a curved wire)

    I initially tried to solve this equation using work, but was stuck in a confusing integral that didn't make sense. I am almost sure that the utilization of energy is needed to solve this equation, but I have been flustered for the past three days at solving this.
  6. E

    Work done by a normal force (or rather, work NOT done)

    This question states that the normal force of the stairs on the woman does NO work. I do not understand how this can be. I would reason like this: The woman propels herself up the stairs using her legs. Her legs push down against the stairs, and the consequent normal force pushes upwards on her...
  7. nav888

    Work done by a force down a ramp

    The mass of the bike and person is 190kg Calculate the average accelerating force from X to Y, if the bike has a velocity of 30 at point Y. I am struggling with this question, I know that Fx = Work Done, but I also know that the only way to release GPE as KE is for gravity to do positive work on...
  8. P

    I Finding the Axis of Rotation with Given CoG and Force Point

    [Mentor Note: See post #10 below for an updated problem statement using LaTeX and with a better drawing] what i want is to find the axis of rotation when the centre of gravity and point on which external force is acting is given along with the magnitude and direction of force. In the example...
  9. A

    I Force Generated By Leg Muscles in Free Body Diagrams

    Suppose a person is walking on the ground without slipping. For the free body diagram of just the person, only the frictional force is drawn in the horizontal direction. The force exerted by the leg muscles to generate a force against the ground is considered an internal force. What would be the...
  10. confused_steve

    I Force Required for Gas Struts on 1972 VW T2 Danbury Pop top campervan?

    Hi all, i'm the proud owner of a 1972 VW T2 Danbury Pop top campervan. Out of the factory these were fitted with 4 x long spring loaded struts which (when new) provided some lifting power to pop the roof up. Mine are now 50 years old and provide no assistance lifting / holding the roof in...
  11. M

    Horizontal force on a horizontal bar

    Tnet = 0 = Tcord-Twall-Tmass TLsinθ-2m(3/4L)-m(1/2)L TLsinθ= -(3/2)mL-(1/2)mL T=m/sinθ T= (1.52)/sin(39.7) = 2.38N
  12. D

    Why is Gravitational Force Proportional to Mass Product?

    why is that the gravitational force proportional to product of masses why not sum of masses or something else .........
  13. L

    B How do I calculate the drop force on a cord and eye bolt?

    i have a question. I have set up an expierment and need some values. I have a round, 3d printed disk, 0.25 inches thick and 4 inches in diameter. In the center, i have a eye-bolt attached. I have hooked up a chain to the eyebolt and some weight to the chain. I have 40Lbs hanging right now and...
  14. G

    I Moment of inertia and contact force

    Two rotating cylinders are held in contact by a force F1. The force is applied through the center of one of the cylinders. One cylinder is the driving cylinder and the other is the driven cylinder . Does the moment of inertia of the system depends on the force contact force F1? Why? And...
  15. sHatDowN

    Determine the moment of the force about point O

    There are components of 500N: 500cos(45)= 353.55 500sin(45)= 353.55 Radius is 3 then M = (353.55*5.12) - (353.55*2.12) = 1060.65is that correct?
  16. salamikorv

    Given force, need to determine what bearing to use for a crane

    Hey! I want to determine what bearings to use for this manual crane and the only thing i know is that it should be able to lift a wieght of 1000kg at max and that the winch should pull 1.24 m of cable/min. Im looking to find the force P to then determine C, and i think P is only the radial force...
  17. S

    My Mistake? Understanding Friction Force & Work Done on Snowy & Icy Surfaces

    The answer is (D), but I don't understand why. Option (A) is wrong because the work done = 0. Then, I divide the motion into 3 parts: 1) motion on snowy surface Since the sledge is being pulled horizontally (let assume to the right), there will be tension force T to the right and friction...
  18. Gixer1127

    How Do You Calculate Tractive Force for Accelerating a Car?

    Hello all, This is my first post so please be gentle with me.. I'm trying to work my way through some tricky questions so will post them below and see if anyone can give me some pointers. The questions are: A car weighs 1305kgs and accelerates from 0 to 160km/h in 4.2s. The first question asked...
  19. S

    Magnetic field force between two perpendicular wires

    There are a couple of problems with the same setup. On plugging in the values and solving for the integral, I am not getting the expected values of the force. Is there something wrong in the solution attached?
  20. Altoid

    Why does the logic of negative acceleration not always indicate negative work?

    Knowing that negative work occurs when the force applied to an object opposes the direction of displacement, and that the direction of acceleration vector should align with the force vector, I assumed the correct answer was that the indication of negative work comes from negative acceleration...
  21. ruivocanadense

    I Covalent Bonds -- Which type of force?

    When you study physics deeper you learn there are 4 types of atomic forces that represent all other in the atomic level (i.e. electromagnetic force, gravitational force, strong nuclear force, weak nuclear force). I always try to see how they manifest in the the atomic interactions. For example...
  22. C

    Force required to strip threads

    Not homework and I'm not a Mech Eng. I was trying to follow a discussion elsewhere about a building foundation that involved 2.75" diameter steel bolts. Two nuts are locked together on the bolt and embedded in concrete. Threads of the bolt itself are sleeved so only the nuts are anchored into...
  23. brochesspro

    I Meaning of the terms in the formula of the net external force

    The mathematical representation of the net external force on a system(obtained from Newton's second law) is ##\vec F_{net} = \frac {d\vec P}{dt}##, which is the rate of change of linear momentum of the system. If we substitute ##\vec P = m\vec v## into the formula for force and differentiate, we...
  24. monsterhart

    1D Particle & Energy w/ F(x): Am I doing this right?

    A) I just did what it said to do: $$\sin\left(4x_{1}\right)=1\implies x_{1}=\frac{\arcsin\left(1\right)}{4}\ m=\frac{\pi}{8}\ m\approx 0.392699081699\ m$$ B) I modified the method from an example from the lecture the other week: $$U\left(x\right)=-\int...
  25. U

    I Question on the Lorentz force: Why is the force not F=q(v×B) = F=qv×qB

    Background: is the equation of Lorentz force for the force acting on a moving charge in electric and magnetic field. For the magnetic field only it is : F=qv×B. Question: For magnetic field only why is the force not F=q(v×B) = F=qv×qB
  26. M

    Finding downward force on immersed object

    For this task, we are meant to immerse objects (held by a mesh) in water to measure the buoyant force and deduce the object densities. We can measure the weight force of the object, ##F_g##, and tension T and buoyancy force. We need to find the downward force on the immersed object, ##F_i##...
  27. Parziter

    Solar System Forces -- Simulating the planetary orbits for my project

    TL;DR Summary: Solar sytem forces on Unity Hello ! For my last year in my school, I've got a project to do, and I wanted to recreate the Solar system with forces on Unity. My forces are Velocity and Acceleration (I'm using the Frenet's formulas). I'm sorry I'm not a physicist and that's why...
  28. M

    Moments of force on Jenga tower

    M= F x d at layer 7, layers 8 - 12 has its centre of mass at middle of layer 10, which is where the weight of these layers would be acting. Not sure hoe to determine whether it would topple
  29. V

    Force between point charges at the center of two spherical shells

    If these point charges were placed in vacuum without any spherical shells in the picture, then the force between these charges would be ##F =\dfrac { k q_1 q_2} {d^2}##. But, I am unable to reason how spherical shells would alter the force between them. I do know that if charges were on the...
  30. Sagittarius A-Star

    I Why Must Pure Force Depend on 4-Velocity?

    Disclaimer: Please read in the following formulas ##E/c^2## instead of ##m##, because W. Rindler used relativistic mass, what might be confusing with today's usage of the term "mass". I am reading the chapter "38. The formal structure of Maxwell's theory" in Wolfgang Rinder's book "Introduction...
  31. Kupa140

    Analyzing the Force of Two Disk Magnets on a Metal Plate

    The situation is as follows. We have two disk magnets. One is fixed on the ground, table, or surface and has the north pole facing up. Then we have a metal plate fixed on the vertical axis rod or something similar such that it can't move up or down, but only rotate horizontally with as less...
  32. sHatDowN

    Vector-Force image and resolve force

    The components of the force of 800 lb F along the non-perpendicular axes Get a, b. Also determine the image F on the axes a, b could some one help me how to resolve forces non-perpendicular.And also what is the meaning of image F one the a,b axes
  33. Remle

    Acceleration & Normal Force of a Box: 4 m/s2 & 418 N

    What is the acceleration of the box? Paper says the answer is 4 m/s2. What is the Normal force acting on the box? Paper says the answer is 418 N. I know that for most cases FN=Fg=W. So, by definition the "original" Normal force is 245.25 N (am I correct?) I calculated the Fay which is...
  34. sHatDowN

    Vector sample problem -- Force components on a spring mechanism

    Determine the amount and type (tensile or compressive) of the spring force so that the resulting force is a vertical force. Also get the resultant force. i find 60N (compressive) and resultant forces is 10800 is that correct?
  35. C

    I Calculating Force Applied to an Object of 100kg Moved 1m in 5s

    if an object of 100kg is moved or lifted to a distance of 1m taken 5s, then how can i find the amount of force applied to the object. in every problem i noticed, force value is given to find the Workdone and the Power. I think it is simple problem, but i can't find it simple. can anyone clear...
  36. sHatDowN

    Vector problem, magnitude of the force

    Member CB of the vise shown exerts on block B a force P directed along line CB. Knowing that P must have a (1237) N horizontal component, determine (a) the magnitude of the force P, (b) its vertical component i don't get it what the "N horizontal component"
  37. L

    B If gravity was a force wouldn't going back in time cause us to float?

    This might sound as a dumb and silly question but if you think about it, it makes sense. If we wrongly assume that gravity is a force just like any other, and given the fact that time is closely related to gravity and that gravitational time dilation is a thing, wouldn't reverse time travel...
  38. K

    How can I troubleshoot and verify my calculations for magnetic force?

    I am getting a wrong answer for part b, however part a and c both are correct : a. 0 N b = -2.91E-3 N (WRONG) c. 1.4E-4 N
  39. KataruZ98

    B Leg muscles’ force as a system of levers

    If I know a person has exerted total force F with their legs and I’m interested in breaking down said force in smaller forces exerted for each involved muscle group - how can I do it? With a basic level of understanding of human anatomy I can divide the leg as a series of levers but how can I...
  40. C

    I How to Calculate force exerted on a falling body?

    I'm curious about impact on falling object, so i have taken initiative to solve this problem. I considered only force on the falling object would be its weight and taken F=mg. With only limited data m=.25kg and drop height h=1m. Pondering on this consideration practically, it will have more...
  41. M

    Infinite number of pairs of Force and distance R from AoR

    For part (b), The solution is However, is there really an infinite number of pairs physically speaking? It would be very hard, say, vary the force applied by ##0.0000001N## for example. Many thanks!
  42. V

    Discontinuity in an Electric line of force

    This is a tricky and difficult question for me. I know from reading various textbooks that electric lines of force are always continuous without breaks, but cannot pinpoint a reason for this. The only reason I can come up is that an electric line of force must always begin and end on charges...
  43. D

    I Question on Hall Effect and magnetic force

    so with a Hall Voltage, you have positive current traveling upwards in a wire in the +y-direction and a magnetic field into the screen in the -z-direction. the right hand rule has positive charge deflecting to the left. now if you look at the drift velocity of electrons moving downward in the...
  44. Pushoam

    Force between the plates of a capacitor with dielectric slab inserted

    The the electric field inside decreases due to the presence of a dielectric by a factor of dielectric constant K. Hence the force between the plates will decrease. Is this right?
  45. C

    Exploring the Relationship between Buoyancy Force and Gravitational Force

    Picture below. Both bodies are made of same material but the body placed in water had 2.4 times greater mass. What is the relationship between buoyancy Force and gravitational force between body in water and body in air?I have no clue how to solve this. I know that body with greater mass has 2.4...
  46. paulimerci

    Find momentum transfer and force on the head with and without a helmet

    Without helmet, m = 4kg, ##v_f = 10m/s## ##\Delta t = 0.0005sec## $$ \Delta p = mv_f - mv_i $$ $$ \Delta p_{without} = 40 kg m/s$$ $$ Impulse_ {without} = F_{net} \cdot \Delta t$$ $$ force_{without} = 80000 N$$ With helmet m = 4kg, ##v_f = 10m/s## ##\Delta t = 0.002sec $$ \Delta p = mv_f -...
  47. M

    Driving force from buzzer for jacket of length L

    For this problem, How do we tell when the buzzer vibrates during the cycle to provide the driving force? Many thanks!
  48. enigmaticbacon

    Converting Effective Mechanical Load to Newtons (Capybara)

    Hello again! I've found the capybara's EMA to be 0.71. Their mass to be 55kg. And their average speed to be ~3.0km/h. I want to figure out how many capybaras it would take to overcome Friction * Normal force of ~125,000N. How would I go about doing that...
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