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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1
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1answer
44 views

generate force accurately

When we like to produce known forces, we know that standard weights acting vertically on a object creates a known force. Now, what are the other methods to generate forces with accuracy. It is a DIY ...
5
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1answer
55 views

How fast until you feel wind in space?

I couldn't find this question asked anywhere else, so I thought I would ask it here: does anyone know how fast you would have to be traveling in space to feel 'wind' from the particles in front of ...
1
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1answer
76 views

Advanced kinematics problem regarding $F = ma$

I really need help with this problem. Thank you for your time. Question: Look at the figure below. Derive the formula for the magnitude of the force F⃗ exerted on the large block (mC) in the ...
2
votes
2answers
143 views

“Magic” Speed to Drive Over a Speed Bump: Myth or Reality?

A somewhat controversial aspect of speed bumps (sleeping policemen for those in the UK) is that they arguably cause more loss of life than they prevent by acting as a hindrance to emergency response ...
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0answers
8 views

Convex and Concave Bridges forces [on hold]

What are the forces acting on a car when travelling in a concave and convex bridge?
0
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0answers
54 views

Electromagnet force equation clarification

So, from a previous previous question, I know what plane the force from an electromagnet will affect a ferromagnetic material in. I thought that would be enough, but working through some problems ...
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2answers
545 views

Punching - Force or Momentum?

If I want to punch a person inflicting maximum damage, what do I need to care about? My force of punching, i.e, do I need more acceleration? Or do I need momentum, i.e my velocity for punching?
17
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6answers
3k views

The best way in which a man can pull a train

I have chosen this example as a paradoxical limit, but my question really regards the optimization, distribution and outcome of force when you try to pull a weight: how can you optimize your ...
0
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2answers
58 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 3 axes (x,y,z) every 10 ms (100 times a second), during a helicopter flight. If one, wants to ...
0
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0answers
27 views

Optimum speed for the highest possible safe transportation of a straight road? [on hold]

By saying optimum speed I mean "Safe Speed". Because in a ice road, the speed has to be low. Whereas the speed in a normal road speed is a reasonable speed. So my question is how do you find the ...
28
votes
10answers
2k views

Where does the extra force generated by a lever come from?

Given an object being pulled down to earth by a force of 1000 lb: If a machine were to lift it off the ground for me, and I grabbed on to the rope before it was released, there is no way in the world ...
1
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1answer
202 views

Does a heavy body move with the slightest force on a frictionless surface?

If I apply horizontal force on a body resting on the ground, my force will be opposed by the frictional force and the body will accelerate at the point where my force exceeds the force of friction = ...
4
votes
2answers
62 views

Can a bullet shot through a glass make a clean hole?

One can often see (hopefully only in the movies) that a bullet shot through a pane of window glass leaves a hole in it, but overall the glass is left largely intact. However, a low-speed projectile, ...
1
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2answers
68 views

Can you punch a hole in an A4 sheet of paper with your hand?

The Heading says it all. But let me explain it a little further. Suppose you hang a sheet of paper (A4 size), from one end leaving the other end free. Now practically it seems impossible to punch a ...
1
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2answers
24 views

Possiblity of predicting behavior of system when properties described as functions over space?

Suppose I am given a system that consists of a distribution of charged particles(which are all over space and are point-charges). They are described by a set of functions instead of variables. These ...
-1
votes
1answer
42 views

Vectors and Forces problem [on hold]

I have a question that I think I have an idea of how to answer but I am unsure can someone please verify for me? Here goes: Here is a box and a force (vector say, F1) of 10 N in the positive ...
1
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0answers
14 views

Kinetic Damping Behavior [on hold]

For a problem I am given a block attached to a spring attached to a wall with mass m and coefficient of friction u. The magnitude when it is sliding is friction=$mgu$ opposite motion. It won't move ...
0
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1answer
23 views

Gravitiation force of a sphere

Was wondering about Shell Theorem, specifically about the immediate results. Force (on a point mass) inside a shell is 0. Force (on a point mass) outside a shell is GmM/r^2 From what i know the ...
0
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0answers
11 views

Statically determinate structures [on hold]

Hello, I'm having trouble understanding why this construction is statically determined. Student in need of critical help.
1
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0answers
46 views

Tension Problem: Solve for T for two sliding blocks connected by a string [on hold]

The problem: Two blocks made of different materials connected together by a thin cord, slide down a plane ramp inclined at an angle θ to the horizontal as shown in the figure (block B is above ...
1
vote
1answer
16 views

Thrust measured in grams and discerning horizontal acceleration?

So, I have a small ducted fan which has a listed "thrust" of 75 g at a set voltage. I'm going to assume the "g" is short for "grams". Why would this be measured in grams instead of newtons and how ...
1
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3answers
301 views

Calculating the torque at a point when a motor is stopped?

So, I'm trying to solve for the torque $\tau_A$ of a motor. I have attached a strong stick to the motor, like so: I apply a force $F$ on the stick which stops the motor. The distance from the ...
1
vote
1answer
40 views

Static and kinetic friction [on hold]

Say you have block1 on top of block 2 and the whole system is accelerating toward the right at a certain acceleration. Due to inertia block 1 wants to move backward to the left so there has to be a ...
1
vote
1answer
33 views

General potential of rotating system

I'm new here at the physics site, and not really that deep into the area of which i'm going to ask a question about now. Therefore please feel free to ask clarifying questions. I'm trying to deal ...
5
votes
5answers
88 views

Forces while squeezing a toothpaste tube

When I squeeze a tube of toothpaste, I am working with 2 squeeze forces toward tube. What causes the toothpaste to go out of the tube? (instead of remaining stationary)
0
votes
0answers
14 views

Truss Bridge project: what is the strongest design for a balsa wood truss? [on hold]

So I have a project in Class and I need to build a truss bridge with only using balsa wood, card stock, and wood glue. My bridge cannot go beyond the span of 21 inches and must support as much weight ...
0
votes
1answer
34 views

Maximum length stretch of vertical spring with a mass? [on hold]

Having a vertical spring, if we hang a mass to it, what is the maximum stretch length of spring? and how big should be mass to break the spring?
1
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2answers
29 views

Diagram of forces exerted on objects

Assuming that there is an interaction between 1 and 3 (they attract each other), what are the forces between 1 and 2? I know it is as if the force acts on a different body (1+2), but I want to know ...
0
votes
0answers
39 views

Definition of force in a scalar field theory

How do we define the force for a general scalar field theory? In particular what is the scalar force of the below equation of motion: where $\tilde{T}$ is the energy stress tensor of matter and $A$ ...
3
votes
2answers
73 views

Why are some forces not included in the sum of forces?

I was given the following notes in class: 4.32 A skier of mass $65.0\text{ kg}$ is pulled up a snow-covered slope at constant speed by a tow rope that is parallel to the ground. The ground ...
0
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0answers
23 views

Effect of an asymmetric weight distribution on a hack squat machine

In a hack squat machine (see figure above), does it matter if I put more washers on one side? May this asymmetry cause an asymmetry of my effort in performing this exercise? For example, if I put ...
0
votes
1answer
33 views

Reflection - reaction force direction

Let's say object hits a wall. When the object is reflected does the direction of the reaction force caused on the wall looks like the red arrow ? Does that direction depends on how "strong" object is ...
0
votes
1answer
23 views

Find distance with zero net electric force [on hold]

I am new to the site (and physics!), sorry if this is too elementary or something. I have this problem that I can not solve - perhaps you could help?! Thank you!
3
votes
2answers
46 views

Why is Buoyant Force $V\rho g$?

For a submerged object, buoyant force ($F_b$) is defined as: $$F_b = V_{\text{submerged}} \times \rho \text{ (density)} \times g \text{ (gravitational constant)}$$ Conceptually, the buoyant force ...
2
votes
1answer
58 views

How to calculate wasted energy

Suppose you are pulling a weight along a track at an angle (in the picture 45°). If the object is dislocated by a distance $D_{45}$ let's assume that the mechanical work done on/energy transmitted to ...
0
votes
0answers
17 views

Action and Reaction on two bodies [duplicate]

If the action and reaction are both equal and opposite then why a body would move? The force exerted by me on the body must be counterbalanced by the force exerted by the body on me.
0
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0answers
24 views

What is the linear and rotational motions generated by a force not on the CG?

Given a force that is applied to a free body, not directly towards, or away from the centre of gravity, how would you calculate the amount of linear and rotational velocities generated, as the farther ...
0
votes
1answer
26 views

Determining the force of an explosion, is it external or internal?

A time bomb put inside a box is left into the vacuum: it explodes...the box coverings starts moving I want to ask: is the force behind sudden acceleration internal or external I am confused about ...
2
votes
3answers
169 views

How do electrons actually move in a circuit?

Last year, we were taught about electricity, about how electrons 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 ...
3
votes
0answers
43 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 ...
0
votes
0answers
25 views

Confusion regarding a method of writing constraint equations

I came across a method for writing the constraint equations known as "The Virtual Work Method".I am quoting the exact language of the text(well,not exactly the exact)- Consider the atwood machine ...
1
vote
1answer
65 views

Question about torque and center of mass [duplicate]

If a yo-yo's string is not attached to anything and the yo-yo is dropped, it is obvious it will fall at $g$. In this scenario, Tension of string = 0. If a yo-yo's string is attached to a cieling and ...
2
votes
1answer
37 views

Why do we exclude the $(i,i)$ case when summing over internal forces?

In the majority of the literature and lectures I see when a system of particles is involved, I usually see the following expression (or similar) for the total force on particle $i$: $$\vec{F}_i = ...
0
votes
1answer
55 views

Figuring out the time period of an Atwood system

SO I was working on Atwoods, when I came up with the following problem, It is more complicated but i should understand this simpler scenario first. As shown in the diagram above, (Atwood machine), ...
0
votes
3answers
3k views

How do I find the tension in additional strings in this problem? [closed]

A mass of 5.00 kg hangs attached to three strings as shown in the figure (see image below). Find the tension in each string. Hint: Consider the equilibrium of the point where the strings join. ...
-1
votes
2answers
35 views

Work done against gravity [closed]

The work done against gravity is $mgh$, well at least that's what my textbook says. I have a question: I can apply a force say 50N, so total work done = $mgh + mah$. Where $ma$ = Force. But the truth ...
0
votes
3answers
203 views

Does the magnitude of an electrical field change with frequency?

I am trying to model the frequency response of a force (dielectrophoresis) that is based on gradient of an electric field. One of the components is the CM factor which has a frequency component, but ...
1
vote
1answer
181 views

Has NASA confirmed that Roger Shawyer's EmDrive thruster works? [duplicate]

This article states: But somehow, despite all of the reasons it shouldn’t work, it does. Scientists at NASA just confirmed it. Now in this question - it is strongly suggested that this ...
0
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1answer
81 views

How to compute speed without knowing mass or charge values?

A gold nucleus is 460 fm (1 fm = 10^(-15) m) from a proton, which initially is at rest. When the proton is released, it speeds away because of the repulsion that it experiences due to the charge on ...
0
votes
1answer
29 views