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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1answer
183 views

Very confused about effective spring constant

I know that for springs in parallel, the effective spring constant is $k_1+k_2$ and for springs in series the constant is $1/(1/k_1+1/k_2)$. But there are some weird problems where finding the ...
-1
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3answers
44 views

Figure out the force constant of a spring [on hold]

You are asked to design spring bumpers for the walls of a parking garage. A freely rolling 1200-kg var moving at 0.65m/s is to compress the spring no more than 0.090m before stopping. What should be ...
0
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3answers
35 views

Drag force - dimensional analysis

I have tried the following example from the link: MIT OCW 8.012 PS1 It is about dimensional analysis. Derive an expression for the drag force on a ball of radius $R$ and mass $M$ moving with ...
1
vote
1answer
279 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 ...
0
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0answers
28 views

How to calculate force needed to launch an object of known mass vertically? [on hold]

I am going to contract a spring and release it to project an object of known mass to a specified distance upwards(vertically).I want to calculate the needed force to overcome gravity and reach the ...
1
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3answers
61 views

Can we reduce a hurricane's power using wind turbines?

Below is the abstract of an article in Nature: Taming hurricanes with arrays of offshore wind turbines, describing computer simulations that indicate that wind turbines could disrupt a hurricane ...
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2answers
26 views

Why are tensions in the pulley different when the pulley has a mass or moment of inertia?

When two blocks are connected by a string passing over a pulley whose moment of inertia is given (means pulley is not massless) then why does the string not have same tensions?
3
votes
5answers
153 views

in Newtons 3rd law, where does the second body get its energy to react?

A very basic question, and apologies if I have overlooked something obvious. In newtons 3rd law, presumably energy is transfered to the second body from the first body (which itself was subject to an ...
-1
votes
0answers
23 views

Three blocks on inclined plane problem [on hold]

I came across this problem on physicsgalaxy.com. My approach: Found limiting friction between 30 kg and 50 kg as 72 N. Found limiting friction between 50 kg and 40 kg as 256 N. Now P+50 sin(37) ...
1
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1answer
44 views

How can we account for a friction force changing sign in a conservation of energy equation?

I want to solve a simple mechanical problem whereby three forces act upon an object. $F_1 = (10 - x)$ N $F_2 = -3 N$ (friction force) $F_3 = -10x$ N So at $x$ = 0 we see that $F_1$ + $F_2$ + $F_3$ ...
0
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2answers
101 views

Question about a car on a banked turn with no friction

A popular physics page explaining how a car can make a banked turn even with no friction : gives the following free body diagram and then says In the vertical direction there is no ...
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2answers
195 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). ...
0
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1answer
653 views

A moving inclined plane with block problem [on hold]

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
2answers
101 views

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

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 ...
-1
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3answers
53 views

Velocity and acceleration with variable friction

If you have a body on a table,with a velocity $u_0$, going from a non friction area to a friction area, how do I find the function for velocity and acceleration due to the variable friction force(T). ...
2
votes
1answer
52 views

induction of van der Waals forces

Is there a way to maximize van der Waals forces between two materials, by electrifying one material, thus creating dipoles/instantaneous dipoles and thus creating stronger van der Waals forces? has ...
1
vote
1answer
64 views

When we ride a bicycle, why do we tend to move left when we turn it right? [duplicate]

When we ride a bicycle, we tend to move our body left if we are taking a right turn and vice versa. Why is it like that?
-2
votes
1answer
25 views

What happens to an object between to massive objects?

I want to understand how forces act on an object. I don't know anything beyond the high school physics so let me ask about gravity. Suppose an object $A$ is placed at the middle of two objects $B$ ...
1
vote
0answers
36 views

Can pair production be used to explain the EM Drive? [on hold]

My understanding of the EM Drive: LOTS of energy and a little light is input into the system. A tiny amount of force is then exerted out of the system. Can this system be explained simply through ...
-2
votes
2answers
49 views

Intitutive meaning the unit of Force $N$

I infer 1 Newton of force = 1 kg.m/ sec squared means a force if acting continuosly on a body at rest would make it gain an acceleration of 1 m/sec squared each second.So the change in velocity is 1-0 ...
4
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3answers
2k views

Why do people with bigger hands/wrists have bigger torque advantages in arm wrestling?

I have arm wrestled people with less strength than me who win simply because they have thicker wrists, or larger hands. It has nary to do with having better technique either, because their wrist size ...
2
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2answers
45 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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2answers
45 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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2answers
62 views

Why are force, momentum, and kinetic energy derivatives of each other [on hold]

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: ...
3
votes
2answers
160 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 ...
2
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7answers
536 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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votes
1answer
46 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
77 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 ...
5
votes
1answer
198 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 ...
-2
votes
0answers
24 views

Calculating deceleration time - help! [closed]

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 ...
0
votes
2answers
280 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 ...
0
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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
81 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 ...
4
votes
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 ...
-1
votes
0answers
36 views

My physics question is about dynamics of a particle [closed]

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
15 views

independent characteristics of force [closed]

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
136 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
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 ...
-3
votes
2answers
57 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
votes
4answers
145 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 ...
7
votes
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
votes
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 ...
1
vote
3answers
61 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 ...
1
vote
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. ...
1
vote
3answers
63 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 ...
0
votes
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
73 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
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 ...