Forces Definition and 1000 Threads

Homework Statement from the notes , the author stated that force has the formula of ρ(L^2)(v^2) and also = ρ(L^3) i think there's something wrong with the ρ(L^3) Homework EquationsThe Attempt at a Solution IMO , ρ(L^2)(v^2) can also be written as ρ(L^4)(T^2) , so Force is proportional to...

If I have a chain suspended from a hook, such that gravity is pulling it downward, how does that gravitational force propagate through the chain? What would happen if the gravitational source suddenly disappeared? What would happen if the hook suddenly disappeared? What I'm interested in, is...

Homework Statement An initially stationary box of sand is to be pulled across a floor by means of a cable in which the tension should not exceed 1100 N. The coefficient of static friction between the box and the floor is 0.35. (a) What should be the angle between the cable and the horizontal in...

Newton's first law of motion is often stated as. An object at rest stays at rest and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an external force. Now for example two people are playing a game of catch. The ball moves in the same...

How come gravity and electromagnetism have an infinite range, while the strong nuclear force dies out quickly? I understand that the weak force's bosons, the W+, W- and Z (neutral), have relatively large mass, and decay quickly, while the photon and the graviton (theoretical carrier of gravity)...

So, I've been looking at this chart Only Electro-magnetic force is carried by massless particle - photon. And it propagates at the speed of light. Now take Weak and Strong force. They are carried by bosons and gluons. They have mass. So, what is the speed of propagation of Weak and Strong...

Hello all Apologies if this is in the wrong section. The below tv show about an air crash investigation makes a statement about forces on a cable that did not ring true to me. I wanted to check my understanding of forces. Simplified as I understood it the following seemed to be suggested...

Homework Statement A body of mass 5 kg is acted on by a force in a straight line. The magnitude of the force after t seconds is given by (2t - 3t^2) kg wt. If the body has an initial velocity of 3ms-1 in the same direction as the force, calculate its velocity after 4 seconds. Homework...

Hi Everyone, I'm trying to justify to myself why |F(a)| > |F(b)| > |F(c)| I think I can see why |F(b)| > |F(c)| due to special relativity case c observed from the charges point of view would observe the charges closer due to lorentz contraction. As the charge is invariant would result in...

We are taught that the forces of attraction in a liquid are lesser than those in a solid. What is the reason? Is it because the intermolecular spaces are large or is it because the individual attractive force of the molecule is less?

Homework Statement When talking about an Atwood machine, a student states: Is the student correct or incorrect? Why? Homework Equations Tension = mg + ma The Attempt at a Solution This is how it is making sense in my mind, but correct me if I'm wrong. I am thinking that the student is...

Hey, I'm having some difficulty in understanding circular motion and it's forces. Here is the situation I'm on: Imagine you are on a smooth turn-table with smooth shoes and the table starts spinning. Because of inertia, and because the frictional force is not nearly enough to keep you going in a...

Homework Statement A 15.0 kg stone slides down a snow-covered hill leaving point A (at the top of the hill) with a speed of 10.0 m/s. There is no friction on he hill between point A and point B (at the foot of the hill). There is friction on the level ground at the bottom of the hill between...

Hello, I would think that it would, because if the wire is longer there is more of a chance of their being foreign objects interfering, which could cause resistance, right? Or no?

Hi, i am an student of civil engineering and i am doing my graduate thesis. so sorry if i misspell, english is not my native languaje. so, here we go :D Homework Statement Before entering in details you (whoever you are) most know: The system is scaled for obvious reasons. The system consists...

Consider we have an iron piece. If we could somehow tap on the iron with our finger for a very long long time, I mean millions of years, would it ever be able to make a dent?

I don't see why the last sentence in the attachment is true. It claims that if ##V_{ij}## or simply ##V## is also a function of the difference of velocities of particles ##i## and ##j##, then the force derived from ##V## is not central. In other words, if ##V=V(|r_i-r_j|, |v_i-v_j|)##, then...

Homework Statement Two identical conducting balls, b1 and b2, each with a mass of 25.0g both are hanging at 50.0cm at an angle of 45Degrees from the vertical each. Homework Equations Fg = mg Fe = kq/r^2 Ft = ? The Attempt at a Solution I made a free body diagram and am confused on what to do...

Homework Statement The question is pretty long and wordy so apologies in advance! Inside the Earth the gravitational field falls off linearly as one approaches the centre. An accurate description of motion in a very deep hole would therefore be to use Newton’s law, f = ma, but with the force...

Homework Statement Hi everybody! As always, I struggle with my special relativity class and here is a new problem I'd like to have some indications about: A masspoint m moves in the x-y-plane under the influence of gravity on a circular path of radius r (see attached pic). Which constraining...

First of all hello everyone, I'm a recent graduate and now I am a mechanical engineer (WEEEEE) and wanted to embark in a project that involves creating artificial forces (Newton's third law kind of forces). The project basically must have something to counter forces exercised by a hand, i.e. if...

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

...Or do they? I read on a book a few years ago that you can spot a conservative force seeing if it depends on the position or not. That means a non conservative force doesn't depend on the position. What is the physical reason for the relationship between a force being conservative and the...

Homework Statement Two tugboats are pulling on a large log, as shown in the following diagram. The log has a mass of 250 kg and is initially at rest. How far have the tugboats moved the log after 10 s? Homework Equations c2 = a2 + b2 - 2abcosC c = (a2 + b2- 2abcosC)1/2 The Attempt at a...

Homework Statement [/B] A 0.5kg wooden block is placed on top of a 1.0kg wooden block. The coefficient of static friction between the two blocks is 0.35. The coefficient of kinetic friction between the lower block and the level table is 0.20. What is the maximum horizontal force that can be...

This is probably a very trivial question, but my brain isn't "playing ball" today so I'm hoping someone can help me with this. Suppose I have a system of ##N## mutually interacting particles, then the force on the ##i##-th particle due to the other ##N-1## particles is given by...

Hello! Capstan law is T2=T1e^μθ. I have problem identifying T1 and T2 in various situations: 1) when the capstan is not rotating 2) when the capstan is rotating how can I identify which side is T1 and which T2? thanks!

In the past I used to understand it in some kind of way. But it doesn't make a lot of sense sometimes. In high school, we usually take examples where the object is placed in an incline and the Normal force is equal to mg cos theta where theta is the angle of the incline. It should equal to that...

Homework Statement Homework Equations F = ma The Attempt at a Solution [/B] I already have the solution, however, I have a few questions. 1)In the solution they have taken m2's acceleration relative to the ground to be a0-a downwards. However, if a>a0, then wouldn't the acceleration...

Hi, I study linear momentum. But I cannot understand enough that how can forces appear on a pipe when fluid flows in the pipe? Fluid have a momentum as m*v how can forces appear on the pipe. I cannot demonstrate the situation in my mind. How can I find a demonstration or a free body diagram for...

I'm curious about contact forces, such as the normal reaction force on a book resting on a table. I've read that it's actually the electromagnetic force, but atoms are electrically neutral and there is no ostensible repulsive force between electrons and the nucleus, so I have some doubts. Has...

Homework Statement pivot point located at the middle of ramp( Point C). F1=250 lbs @ 12 in from point A F2=250 lbs @ 84 in from point A L=192 in angle from the ground is 25 degrees Homework Equations sum of moments equal to 0 sum of forces equal to to 0 The Attempt at a Solution I did sum...

Homework Statement Word problem. Fisherman lifts a trout with his fishing rod directly upwards. The fish is a trout. The trout's mass is 0,45Kg. The trout's acceleration is 2,5m/s^2. a) draw free body diagram for the trout b) with how great a force, does the fishing line affect the trout...

Earlier today I was reading through this entire thread: https://www.physicsforums.com/threads/implications-of-the-statement-acceleration-is-not-relative.670653/ And I remained confused about one thing in particular. The original poster made a statement (bolded below) on page 1 that seemed...

Homework Statement A stationary bicycle wheel is placed on its rim on rough ground. It topples over. Sketch a free body diagram for the wheel when it is at an arbitrary angle to the vertical and label the forces. Explain qualitatively what happens to the direction and magnitude of each of the...

I'm wondering how should I do analysis on those problems below: Figure 1: Figure 2: I mean, my professor, while doing an example very similar to Figure 2, he didn't do an imaginary cut in the region BD to find internal forces there, and the internal forces diagram that he drew only contained...

Homework Statement Homework Equations sum of forces in x and Y = 0 sum of the moments at a point = 0 Ffr = normal force * friction coefficient The Attempt at a Solution Im just trying to make a start, I am struggling to wrap my head around the basics with this question. Do you guys think...

In the above case, the normal force exerted by the elevator on the box would be = 10kg * g + 10kg*5m/s^2, assuming g = 10m/s^2, the elevator would exert a normal force of 150N on the box. But wouldn't the box exert an equal and opposite force on the elevator resulting in no motion? I know this...

Homework Statement My teacher said that if you are holding an object in your hands and lowering it downwards, you are applying force in the upwards direction. How does this make sense and are there any other cases where the direction of an objects force is opposite the direction of its motion...

I apologize if my thought process is unrefined. I didn't really learn and remember much from high school physics that benefits me right now in college physics. Until this point we covered Newton's three laws of motion. And instead of a cotton ball, we used a coffee filter. "Our reasoning is...

Is there a name or phenomenon of the feelings the passenger gets that the driver does not? Example: A driver of a car feels that they are driving smooth and comfortable, yet the passenger feels like they have to hold on to the door handle and feels that the ride is rough. If the two folks in the...

I find difficulties in identify the forces acting behind the acceleration of objects that are considered consequence of conservation principles (for istance of KE and angular momentum). I'll make an example to explain. The same string-mass system is linked to a rod. In case (a) a force pull the...

Homework Statement A small textbook is resting on a larger textbook on a horizontal desktop. You apply a horizontal force to the bottom book and both books accelerate together. The top book does not slip on the lower book. What forces causes the top book to accelerate horizontally? Homework...

Homework Statement An alpha particle (charge equals +2e) is sent at high speed toward a gold nucleus (charge equals +79e). What is the electrical force acting on the alpha particle when it is (2.0 x 10-14) m from the gold nucleus? Homework Equations I tried using Coulomb's law, which is E =...

Hello all, I have a (at what first seemed) fairly simple question about calculating the forces on this fulcrum design I have. Here is an image of the sketch and free body diagram that I drew: Basically, the pivot point in my real life application is actually a cam, but for the sake of this...

Can someone check if my Sum of All Forces is setup correctly? Problem: Diagram: http://puu.sh/o6pLY/285d7b12c1.jpg Sum of all Forces:

I don't know if my ΣFin is correct I am having trouble setting it up. Can you check if the new diagram and the component setup is right? Problem: Work:

To me the force P that pulls the bottom block up the incline seems a little low. Can someone confirm with my setup and work in brown is correct? Thank you. Problem: Work:

Let's assume that the force of friction is only present between the two blocks and that the pulley is massless. On top of that, force F pulling the two blocks at a constant velocity; as a result, the acceleration = 0m/s2. May someone tell me how many forces of friction are going on between the...

Can someone help me relearn finding the angle between two forces when solving for work of each forces (gravity, tension, fF, normal)? I remember that cos(90°-α) = sin(α) but what I don't understand is when the angle in between is "90°-α" or when it's just "α". I tried doing this on my own and...