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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Why are force, momentum, and kinetic energy derivatives of each other

Force $ma$ is the rate of change of momentum, or the derivative of momentum with respect to time $$\frac{d}{dt} mv = ma = F$$. Kinetic energy is the integral of momentum with respect to velocity: ...
2
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7answers
523 views

Free fall into circular motion

If I'm on a roller coaster free falling from height $h$ and then suddenly start going into horizontal motion with a radius $r$ of turn what is the $g$-force I experience? I worked out the equation ...
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2answers
32 views

When is work done on or by something?

An example, here what my textbook says: When charges are released In electric fields charges experience the force causing them to accelerate along electric field vectors. Positive charges ...
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1answer
41 views

How long will pressure exist in this case?

I'm currently fabricating my project, which currently exists only on paper, and there's one question to which I have stumbled today. Suppose, that I have a pressure vessel capable of holding upto ...
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2answers
73 views

How to solve this pendulum problem using kinematics, not the principles of conservation of energy?

I have this question, because typically problems that can be solve using conservation of energy or just energy-related principles, can usually be solved sing kinematic equations. (At least is what I ...
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1answer
68 views

Why can I put my hand through sand but not a table?

I've read in books that one can't put one's hand through a table because the table offers a "Normal Reaction" to the hand. And it is also stated that this force is electromagnetic in nature. But what ...
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1answer
197 views

Force problem related to adhesive and bonding

I have two PCBs (printed circuit board), and they are glued by adhesives, as show in the pictures. And the location of the adhesives are indicated on the picture (please notice that NO adhesive is ...
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0answers
29 views

Distribute force over a rod

Well, the idea is that I have a rod of length $L$ and force $F_0$. Now I have to distribute those $F_0$ Newtons on the rod. But the problem is, that I want to do it continuously. So what I want in the ...
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0answers
22 views

Calculating deceleration time - help! [on hold]

I'm struggling with a question due to not having the correct formula, so I hope someone can help! A 10000kg object is travelling at 15m/s, and a force of 600N is applied in the opposite direction to ...
2
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2answers
121 views

Does the outflowing water create a thrust on the bucket?

Let's consider the the bucket with water, which has a small hole at the bottom. Let the bucket lift up with a constant force $\vec F$. Water in the bucket, of course, flows out of it. Questions are ...
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2answers
279 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 ...
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3answers
64 views

Which one of the two objects does the gravitation force vector point to?

My book tells me that the arrowhead should point to whichever is responsible for the field. Am correct in a assuming that it's whichever has the larger mass or bigger electric charge?
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2answers
66 views

Magnetism and Photons

Knowing that magnetic field is made from photons. Where does a magnet gets it's photons from to create a magnetic field. Are the photons created within the magnet, or does the magnet capture photons ...
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1answer
54 views

Finding minimum time to raise a bucket

First of all, I wonder: in $F=ma$ does the acceleration have to be constant? I believe so but, just as confirmation. Problem: A 4.80 kg bucket of water is accelerated upward by a cord of ...
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0answers
34 views

My physics question is about dynamics of a particle [on hold]

A body of mass $2$ kg is acted upon by two forces each of magnitude $1$ Newton, making an angle of $60^{\circ} \simeq 100^{\circ}$ with each other. The net acceleration of the body (in ...
-1
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0answers
14 views

independent characteristics of force [on hold]

I would like to know whether there exists independent characteristics of force or not. I read somewhere that the force does not posses independent characteristics. Is it correct? Support your answer ...
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2answers
135 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
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1answer
12 views

How to calculate the “angular braking distance” when you know the following values?

I have to calculate the arc length in radians that a circle spinning at speed will travel when it decelerates to $0$. I have the initial angular velocity in rad/s, the radius in meters, the mass in ...
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2answers
54 views

Spring balance: what will be the reading? [duplicate]

There are two cases: When the two forces say L (for left) and R (for right) are equal. F=L=R What will be the reading? I know the reading would be F but why? When the two forces are unequal that ...
2
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4answers
143 views

What exactly is work?

What exactly is work? My book confuses me: a force can lift an object to a height h, or it can accelerate an object through gravity. In all these cases, a force displaces an object and change the ...
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6answers
1k views

Why is friction force negative in ice skater problem?

A 68.5 kg skater moving initially at 2.40m/s on rough horizontal ice comes to rest uniformly in 3.52s due to friction from the ice. What force does friction exert on the skater? I am not really ...
3
votes
1answer
165 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 ...
14
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5answers
1k views

How to sail downwind faster than the wind?

Recently a group set a record for sailing a wind-powered land vehicle directly down wind, and a speed faster than wind speed. Wikipedia has a page talking about it, but it doesn't explain exactly how ...
2
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1answer
30 views

Force division of moving pulleys?

I am a second grade at a middle school and I was reading a physics workbook to prepare for a test. And I was solving pulley problems and one problem made my brain stop. The problem asked me what ...
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3answers
60 views

Is there a general rule for determining the direction of tension force?

Tension, for me, is a tricky thing. After finishing a related chapter of my book and watching a video, I still can't get a hang of it. Here is a situation: My knowledge is that tension, just like ...
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3answers
41 views

Is work-kinetic energy theorem useless?

This is how my book explains it: $W_{net} = \delta K$ Since the net work is tied to changes in kinetic energy and changes in speed, a mass must accelerate in order for net work to be nonzero. ...
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3answers
62 views

Trajectory of rolling billiard ball after collision with another billiard ball with same mass

So, according to this article http://www.real-world-physics-problems.com/physics-of-billiards.html , the trajectory of white (cue) ball is always perpendicular to the line connecting center of ball ...
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0answers
26 views

Force applied on object moving in circular direction [closed]

I should start by saying I am not a physics expert, but I need to know the below. I have tried searching the web for this information but I was not able to find anything more than angular velocity and ...
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votes
1answer
21 views

What is the net force [closed]

A net force of 1.00 newtons accelerates an object at 5.00 meters per second per second. What net force would be required to accelerate the same object at 10.0 meters per second per second?
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votes
1answer
27 views

Find magnitude of force [closed]

A $15.0\,kg$ shopping cart is accelerated uniformly from rest to a speed of $2.00\, m/s$ in $1.50\, s$. What is the magnitude of the force producing this acceleration?
0
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1answer
20 views

Why in some cases normal force does not equal apply force that is in line with the normal force? [closed]

My understanding is that normal force is always equal to the applied force vector that is in line with it. Like weight going down, normal force going up along the same line, equal in magnitude. Here ...
0
votes
1answer
71 views

Can a train with magnets attached move with less fuel?

For a train, if we attach magnets ( big ones ) such that, for each compartment north faces front and south faces back, can that train move. So if this is right, we can move a train by just moving the ...
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0answers
36 views

Inclined plane problem - admission exam [closed]

This following problem was featured on my Physics admission exam and I didn't know how to approach it properly : Consider an inclined plane at an angle $\theta = 45 ° $ of mass $M = 9 kg$. On the ...
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0answers
11 views

How do you calculate the optical contact bonding force of 2 1 meter by 1 meter perfectly flat surfaces?

Optical contact bonding is a phenomenon in which two perfectly flat surfaces will stick together, held purely by intermolecular forces. The trouble is, is there a way to calculate the pressure between ...
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2answers
50 views

If you place a filled water bottle at the bottom of the Mariana Trench, how does the bottle stand the enormous pressure?

The pressures are akin to an entire train pressing down on you. How does the water bottle stand this pressure? And yes, the water bottle will stand: How else do the creatures at the very bottom of ...
3
votes
4answers
428 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 ...
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4answers
238 views

What is the *cause* of the Lorentz Force

Is it possible to explain what actually causes the force on a current carrying conductor in a magnetic field. I have read that this is due to the magnetic fields 'interacting' in some way. This ...
3
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3answers
88 views

If gravity were to suddenly change, would the lift generated by a airfoil also change [closed]

If gravity were to suddenly change, would the lift generated by a airfoil also change? I realise that if gravity were to increase, then weight would also increase, leading to a change in the ...
-1
votes
2answers
51 views

How do I calculate the weight that PSI can lift?

Imagine that there's a force that is given to you in $psi$, say $1450\ psi$. And there's some body of weight say, $100\ kg$. What I want to know is that, how much $psi$ will I need to lift the "body" ...
1
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3answers
50 views

Force to deflect ball colliding with wall

Suppose I have a ball with a certain coefficient of restitution. The wall can be considered indeformable and with infinite mass. Everything's in 3 dimensions, and the ball can hit the wall at any ...
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1answer
98 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), ...
3
votes
2answers
62 views

Pulley-rope tension question

I'm learning mechanics and I don't understand the following (simple, I guess) concept. Here's a pulley-rope system: The force of tension, as I understand it, is defined as the force exerted on an ...
-1
votes
0answers
30 views

Finding the minimum Force [closed]

As shown in the picture.force(F) is acting on two masses. There is no friction between (M) and the surface.the friction between (m) and (M) is (mu).the system is moving because of the force and ...
0
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2answers
83 views

How this formula for work follows from the definition?

If a particle moves along a path $\gamma : I\subset \mathbb{R}\to \mathbb{R}^3$ then the work done by a force $\mathbf{F}$ is defined by $$W = \int_{\gamma} \mathbf{F} = ...
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3answers
103 views

Neutrinos travels through our bodies: do they contribute for gravitational atractive force?

Are neutrinos traveling through our bodies what really make us attracted to the Earth?
1
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2answers
53 views

Why things wobble when submitted to wind?

If I place a little piece of paper in front of a fan, it is going to wobble/oscillate. Is it because the wind flow isn't constant ? Or because the air movement makes the piece of paper move away, so ...
3
votes
1answer
40 views

Would a solenoid move if a magnet went through it?

If you were to have a solenoid (0 current) floating still in space, and shot a magnet through it, would the solenoid move, or would it only create a DC current (what if it has a closed/open circuit)? ...
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3answers
58 views

How to apply Newton's first law to moving object?

I'm new to many forces, such as gravity and friction, and I don't really know how they work. I'm trying to simulate a ball bouncing with a program, and it travels at a constant speed horizontally. I ...
5
votes
2answers
300 views

How does one write Newtons 2nd Law using the language of forms?

Newton's second law says that $F=ma$. Supposing that the force is conservative and can thus be expressed in terms of a potential $V$ we have that $F=-dV$. We have that $V$, being a function, can ...
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1answer
36 views

Net work done by projectiles?

When the projectile is in motion what is the net work done on projectiles? What i think? 0 first view: We know when we throw projectiles the initial KE and final KE is 0. So from work energy ...