This tag is for the classical concept of forces, i.e. the quantities causing an acceleration of a body. It expands to the strong/electroweak force only insofar as they act comparable to ‘classical’ forces. Use [tag:particle-physics] for decay channels due to forces and [tag:newtonian-mechanics] or ...

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2
votes
1answer
33 views

Distribution forces

I've got two trees and between them is a rope. When someone about 100kg sits at the center of the rope, what are the forces on both parts of rope (to the left-hand side from the person and right-hand ...
0
votes
1answer
571 views

A moving inclined plane with block problem

I'm trying to solve for a challenging problem : a moving inclined plane with a block I want to solve for the acceleration components for the block and the plane and the normal force acting on the ...
1
vote
1answer
265 views

Force due to combination of free space and dielectric

I will make a generalized form of my question. There are two point charges $q$, $x$ distance apart. And there is a dielectric slab of thickness $t$ and of dielectric constant $K$. Should the force ...
-1
votes
0answers
20 views

Why friction increases with increase in normal force?

Why is friction dependent on normal force and not the actual weight? I have also read that friction is horizontal component of contact force. Is this true?
1
vote
2answers
458 views

How does this chair move?

I have a chair like this(shown in figure). I was kneeling on the part where we sit. I just gave a sudden push to the part where we rest the back, without moving my legs. I found that the chair is ...
-1
votes
1answer
22 views

Central Force - Trajectory [on hold]

There is a central force $\vec{F}(\vec{r})=f(r)\vec{e_r}$. 1.1.: The trajectory/flight path is defined by $r=r(\phi)$, compute $f(r)$. 1.2.: The path is defined by $u=u(\phi)$ with ...
0
votes
0answers
30 views

Can a magnetic field be expelled over long arbitrary distances through a super conductor? [on hold]

I'm not a physiscist but i have a creative concept I wish to make into a environmental commercial before my Interactive Feature Film. Apologies, if it sounds like I have no idea what I'm talking ...
-1
votes
0answers
27 views

Central Force - Trajectory [duplicate]

There is a central force $\vec{F}(\vec{r})=f(r)\vec{e_r}$. 1.1.: The trajectory/flight path is defined by $r=r(\phi)$, compute $f(r)$. 1.2.: The path is defined by $u=u(\phi)$ with ...
2
votes
1answer
27 views

Force needed to roll wheel over edge [on hold]

I'm looking to find F. See image below. What we know: Mass of the wheel: $ m = 14 $ kg Wheel radius: $ r = 0.32 $ m What I've tried so far: $$ mg + N + \sin(38.7)k = 0 $$ Once the wheel ...
1
vote
0answers
17 views

Force acting on a wheel of a two-wheeled self balancing bot

Proceeding further with my work on a self-balancing bot as posted here: http://bit.ly/1FfI6LK I've gotten stuck at the following equation: n = Gear ratio $K_t$ = DC motor torque constant $i_l$ = DC ...
5
votes
5answers
1k views

Kinetic energy vs. momentum?

As simple as this question might seem, I failed to intuitively answer it. Let's assume there is a $10,000$ $kg$ truck moving at $1$ $m/s$, so its momentum and KE are: $p=10,000$ $kg.m/s$ and ...
0
votes
1answer
29 views

Finding the tension in a rope with mass defined per unit length [on hold]

A rope of length L has its mass per unit length λ varies according to the function λ(x)=e^x/L. The rope is pulled by a constant force of 1N on a smooth horizontal surface. Find tension in the rope at ...
1
vote
1answer
38 views

Relativistic Lorentz Force with constant, perpendiuclar, and uniform E and B fields

I am trying to solve the following problem from the Fundamentals of Plasma Physics by Bittencourt (Problem 2.7): Analyze the motion of a relativistic charged particle in the presence of crossed ...
3
votes
1answer
99 views

Is it possible to apply force to a light particle?

I know, the universal speed limit is the speed of light $c$. So, is it possible to apply more force to a light particle? What would happen to it if we could?
3
votes
1answer
287 views

Acceleration: A ball sliding down the inside of a semicircular bowl

Edit: To clarify, this is a homework question. But I couldn't care less about getting the answer to this specific question as it's not even assigned yet. It looks interesting and I want to understand ...
1
vote
2answers
43 views

Static friction and Kinetic friction

I can't seem to find this anywhere on the internet or on stack... Sadly. Very basic question: I have a block that is on a surface. The coefficient of static friction between the two is $0.3$, ...
3
votes
1answer
291 views

Large deflection of cantilever beam

How can I find the amount of point force at the end of a cantilever plastic beam that produces e.g. 45° slope at the end of the beam? Is this the right equation: $$F=\frac{2EI\theta ^2}{L^2 ...
0
votes
0answers
61 views

Why Does Moving a Cup of Coffee Up and Down whilst carrying it Make it less Likely to Spill?

Sometimes I have a Very Full Mug of Coffee and I am trying to carry it without it spilling. I noticed that if I moved the Mug up and down when carrying it, it seemed to settle the coffee and make it ...
2
votes
3answers
6k views

Rotating a stone with a string

Suppose we are given a stick and a stone tied to the stick by a string. Now if we rotate the stone around the stick the stone rises in height (see picture below). My question is which force accounts ...
4
votes
5answers
221 views

$F=ma$, so if acceleration is zero the force must also be zero?

I was just pushing a huge rock which I couldn't move at all. Given that the acceleration was zero as a result of my efforts, since $F=ma$, doesn't this mean that the force must also have been zero? ...
1
vote
1answer
1k views

Why is the mechanical advantage of a wedge = length of slope/ width?

Mechanical advantage is defined as Force Output/Force Input For a symmetrical wedge with the length of the slopes being equal and the width being the distance between the end points, the articles ...
0
votes
0answers
19 views

Find direction and magnitude of net electrostatic force on a point charge [on hold]

Question: Find the direction and magnitude of the net electrostatic force exerted on the point charge $q_2$. Let $q = +2.4μC$ and $d = 33cm$. What I tried: I used the formula $F = kq_1q_2/d^2$ to ...
-1
votes
0answers
22 views

Finding displacement of spring [closed]

Q) A block lies on a horizontal frictionless surface, and the spring constant is $50\,\mathrm{N/m}$. Initially, the spring is at its relaxed length and the block is stationary at position $x=0$. ...
0
votes
0answers
27 views

The minimum force required to lift a triangular prism [on hold]

If I have an isosceles triangular prism of mass m with the angle at the top being $2\theta$ I want to work out the minimum force I would need to apply to the upper faces to lift the prism. Lets say ...
2
votes
2answers
45 views

How can tangential acceleration from a radial force be explained?

A mass is attached to a rope, and put into a circular motion. If I pull the string from the center, the tangential speed of the mass will increase (by conservation of angular momentum). I am ...
0
votes
2answers
89 views

Good way to compute the force of a hammer blow?

What is a good and easy way to compute and/or measure the force of a hammer blow, not using any fancy or specialized equipment? If the hammer is swung by hand through an arc, it is not obvious to me ...
32
votes
10answers
17k views

How exactly does curved space-time describe the force of gravity?

I understand that people explain (in layman's terms at least) that the presence of mass "warps" space-time geometry, and this causes gravity. I have also of course heard the analogy of a blanket or ...
0
votes
2answers
242 views

Advantages/Disadvantages of “hanging off” a motorcycle when leaning

The closest question I could find with regards to this subject was this one: Countersteering a motorcycle However, it does not address the specific physics of what I would like to know. There are 3 ...
3
votes
1answer
136 views

Force field for Calcium ions, potassium ions and water in molecular dynamics

I want to adapt my existing MD simulation so that it can handle these three species. For the interactions of the ions I thought that I would use the coulomb potential, but I don't know what sort of ...
2
votes
1answer
120 views

What are the proposed theoretical explanations for the EmDrive?

The EmDrive is a proposed propulsion mechanism for spacecraft in which some form of microwave device provides the propulsion. The consensus from the physics community, including many voices on this ...
1
vote
1answer
147 views

Force of a solenoid on a ferromagnetic material

As I was trying to find an answer to another problem, I was informed that the equation I was using would not work. The equation I was using was $$F = (NI)^2\mu_0\frac{\text{Area}}{2g^2}$$ If this ...
1
vote
1answer
39 views

Maximum angle for highway lane change

I am preparing to fight a traffic ticket from a speed camera. There is a lot more to that story, but the info I need right now involves the angle at which a car can change lanes, in terms of vehicle ...
0
votes
3answers
99 views

Can two electrons attract each other?

Due to electrostatic repulsion the two electrons will repel each other as they both possess similar charges, lets leave gravitational attractive force out of the picture my question is can there be ...
0
votes
2answers
169 views

Ball flying towards me - Newton's third law is violated?

I was trying to answer the question of the flying ball here on the basis of Newtons third law and Momentum conservation. Here is what I have tried. Lets take $m_1$ (the ball) hits $m_2$ (the man). ...
1
vote
0answers
30 views

Potential (which only depends on the length of a position vector) [closed]

a) A potential $U$ only depends on the length $r=|\vec{r}|$ of the position vector $r$. Show that $$\vec{\nabla}U(r)=U'(r)\frac{\vec{r}}{r}. $$ What properties does this vector field have? ...
3
votes
2answers
139 views

How to use an accelerometer to correctly quantify the magnitude of vibrations

Consider the following setup: An accelerometer is placed inside a helicopter, measuring $g$ values along three axes $(x,y,z)$ every $10~\text{ms}$ (100 times a second), during a helicopter flight. ...
0
votes
0answers
67 views

Centrifugal And Centripetal Forces [closed]

Imagine a long rod floating in space(negligible gravity). On this long rod are attached 8 other smaller rods with a massive sphere attached to them at the end. They are connected with the long rod ...
0
votes
2answers
106 views

Work and Free Body Diagrams

I am a bit confused with how to find work when there is a free body diagram. I am trying to work out this problem, and in it a box is being pulled at a constant speed by a rope at a constant angle ...
0
votes
1answer
27 views

Friction on a body

Consider a cuboidal block kept on a table with friction coefficient $\mu$. When calculating the friction, we use $f= \mu n$ where $n=mg$ for a horizontal table. But a pressure due to the atmosphere ...
4
votes
3answers
620 views

Work = Force x Distance vs Displacement

The difference in using Distance vs Displacement is demonstrated in this example: Work = Force x Distance If I carry an object to and fro 10 metres, the work done would be Force x 20 metres. ...
1
vote
2answers
37 views

In which direction does mud fly off a moving bike's tire & why?

If a bike moves through a muddy area, mud gets on its tires. Then the mud flies off from the tires. Which forces are acting on it? In which direction does it fly off? On my physics test, I wrote ...
3
votes
3answers
364 views

How do electrons actually move in a circuit?

Last year, we were taught about electricity, about how electrons move in a closed circuit. But as our teacher had not taught us about electric fields yet, she gave us a simplified model of motion of ...
-1
votes
1answer
26 views

How would change force of gravity? [closed]

How would change force of gravity, impacting some object, when this object is lifted on height $h = 3 \cdot R_3$. The right answer stated as ("decrease 16 times"). I want to know why.
1
vote
1answer
10 views

Is the index of time in the unit equivalent to force dependent on the number of dimensions

When the unit of force is represented as $\text{distance per time}^n$ in 3 dimensions $n$ is equal to 2. Is n also equal to 2 for higher or lower dimensions (2D, 4D, 5D, ...) or is it dependent on the ...
0
votes
3answers
52 views

Question on normal force and static friction [closed]

Why is this statement false: If the normal force on an object increases, the static friction must increase? Thank you! Is it because they did not state what normal force is referring to?
2
votes
3answers
363 views

Why do non-accelerating objects exert force on each other?

The equation for force is $\vec{F} = m\vec{a}$, where $\vec{a}$ is acceleration. Acceleration is a change in velocity. However, if an object with constant velocity (i.e. 0 acceleration) hits another ...
0
votes
0answers
14 views

How this tube rotates? [duplicate]

I recently seen a video where a tube is spin into space. When it starts to rotate, it keeps continuously to rotate along the axis of 180 degrees clockwise, then 180 counter-clockwise and so on. The ...
0
votes
1answer
83 views

What are the equations for the weak and strong forces?

What are the equations for the strong and weak force, like how for the Electrostatics the equation is $F_c= k*Q*q/(r*r)$. I understand to an extend what the strong and weak forces are. However, I ...
2
votes
4answers
360 views

What causes a car's velocity to follow the front wheels' direction?

I'm trying to simulate a car with correct physics models. In this example we let the car have a constant speed, and there are no forces (friction and drag) to slow down the speed. Here's a video that ...