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
24 views

The nature of universal forces

When we speak of universal forces, do these forces constitute a form a matter? Are they consistent forces throughout the universe? Meaning, are there regions of space where these rules don't hold up ...
2
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1answer
52 views

Conservation Of Angular Momentum of a falling stone

I am currently stuck on the following question. A stone is dropped from a stationary helicopter 500m above the ground, at the equator. How far from the point vertically below the helicopter does it ...
0
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1answer
41 views

3 pulley and 2 masses,relation between their accelerations [on hold]

I want to find acceleration of each mass in this system. lets take length of rope between three pulleys as $L$. then we can use this relations ...
0
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1answer
29 views

A conceptual understanding of kg*m/s/s

Force is measured in kgm/s/s, or rather the rate in change of the rate in change of mass times length. Conceptually, what might the product of mass and length be? If force is the second derivative of ...
0
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0answers
47 views

Force and Displacement: which come first? [on hold]

In nature, does force generate displacement, or displacement generate force? For instance, a spring oscillator, whenever you give a force, the displacement comes along and you will feel reaction ...
3
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2answers
195 views

When objects fall along geodesic paths of curved space-time, why is there no force acting on them?

On cseligman.com, it is written that So, we see things falling with an acceleration which we call the acceleration of gravity,and thinking that we live in a straight line , uniformly moving or ...
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2answers
95 views

Do objects really move in the direction of the force applied?

According to the second law of motion: Direction of the force is in the direction of change in momentum. Now, I came before a problem. Though an easy one, I was perplexed at a point. A ...
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0answers
41 views

Can someone please explain the forces acting on the rod? [on hold]

Can someone please explain the forces acting on the rod.
5
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5answers
89 views

The elusive difference between force and impulse

Impulse is defined as the product of a force $F$ acting for a (short) time $t$, $J = F*t$, and that is very clear. What I find difficult to understand is how a force can exist that doesn't act for a ...
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0answers
26 views

Inclined pulley. Finding the $\frac{M_1}{M_2}$ [on hold]

Problem As you can see in the picture, $M_1$ and $M_2$ are attached by a massless rope over a pulley. the height difference of $M_1$ and $M_2$ is $h$. The masses start to move and after $τ$ seconds, ...
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2answers
2k views

Why is the equation for friction so simple?

The general equation for the force of friction (static or kinetic) is $F_f = \mu * F_N$, where $F_f$ is the force of friction and $\mu$ is the coefficient of friction (its value is dependent upon the ...
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1answer
40 views

Action and Reaction - Time lag

Is there a time lag between action and reaction ? If there isn't such a time lag, the reaction force must cancel the applying force although they act on different bodies. My second question is that, ...
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3answers
47 views

Do components of force have direction when doing work?

When we get angle > 0, the x-component of force is along the direction of displacement and so their product is called Work. So the x-component of force is said to have direction of the respective ...
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1answer
27 views

How do you work out the energy requirement for a submerged pump?

I was wondering if you were to place a pump in a submerged container and then were to open a hatch allowing water to flood the previously vacant cavity how much energy would be required to discharge ...
3
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1answer
63 views

Are fundamental forces always attractive/repulsive, i.e. parallel to the separation?

If magnetic monopoles existed it would not be the case - the forces on an electron and a magnetic monopole passing by each other would be at right angles to the vector connecting the two particles! ...
0
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1answer
74 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). ...
2
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2answers
57 views

How to actually account for air resistance?

What's interested me in my studies thus far is that in a lot of beginner undergrad mathematics and physics courses we're often told to calculate trajectories, velocities, etc. by "ignoring air ...
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2answers
40 views

Inclined pulley with unknown hanging mass: when won't the system accelerate?

We have an inclined pulley with angle of $30° $ a block with mass of $10 kg$ placed upon it and It is attached by a rope over a pulley to a mass of $M_A$ which hangs vertically. If $μ_s=0.4$ and ...
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2answers
88 views

Force of a Train

Imagine that there are two trains and the first train is twice as long as the second train. They have the same mass per unit length and they are traveling at exactly the same speed. If the first ...
1
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1answer
27 views

How do you find the tension in the real world? (Given a rope in a pulley system)

I'm well aware of the formula to calculate tension, however, given a real world situation where you have a closed pulley system. How do you measure the force (i.e., tension) required to pull on the ...
0
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1answer
46 views

Problem of uncoupling a train

As a kid I have seen several movies, cartoon etc. in which usually one guy just uncouple (unplugs (?), dunno) the rest of a running train and then runs off with the locomotive at full speed and ...
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3answers
49 views

Net force of the following? [closed]

The following objects are attached to one another and have difference force directions: Where is the direction of force? And What is the net force? I'm trying to calculate it using their angles, ...
2
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2answers
44 views

Another condition of calculating work

Let's imagine that there is a box placed at the corner of a table, and I push it so that my applied force makes an angle of 30° from the table's surface. The box would move and, due to the effect ...
0
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3answers
64 views

Why doesn't an object that collides with one that is at rest just do a 180?

Newton's third law says "for every action, there's an equal and opposite reaction." So why is it, say, that when a pool/billiards ball hits the wall of the table, the ball doesn't just turn around?
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1answer
40 views

spinning a water bottle quickly

When we spin a water bottle so quickly, why don't the water inside the bottle come out ? It has to do with the normal force and the apparent weight , i think . but plz someone explain for me how does ...
0
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2answers
86 views

Why the gravitational force is 10^38 times smaller then the strong nuclear force?

and the weak interaction force is $$10^7$$ times smaller then the strong nuclear force? Why exists this comparison?
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1answer
48 views

Two boys pull a rope in the two edges with the force 50 N each. Will the rope rip if it can handle only a pull of 80 N? [closed]

I think we should make the sum the two forces 50+50=100 N and say it can't handle? Can you explain me using the 3rd Newton Law?
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1answer
20 views

About Cell and its electric feild?

1.When we connect wire in a battery there is a electric field so current starts flowing? 2.Do electric field spreads everywhere except in wire? 3.Electric field starts from positive charge to ...
1
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1answer
43 views

What happens when a force is not applied on the centre of the mass? [duplicate]

The answer to this question force applied not on the center of mass states that for a force applied not directly on the center of mass will have the same linear acceleration as one applied on the ...
18
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6answers
3k views

Conservation of momentum when rain pours into a wagon

Suppose a wagon is moving at constant velocity on a friction-less surface, and rain begins to fill the wagon. The net force on the wagon is zero, so momentum is conserved; as the mass of the wagon ...
0
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2answers
27 views

Tension of 2 massless springs joined together

A cable is formed by joining two massless springs with different spring constants. Spring A has constant k1. Spring B has constant k2. If mass M1 hangs from the cable, is the tension greater on ...
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1answer
28 views

Understanding tension principles in a 2 pulley system [closed]

Trying to understand tensions in a 2 pulley rope system, where M1>M2. Is it true that T1>T2>T3?
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2answers
27 views

Modeling external forces in Lagrangian dynamics

For example, consider a system with a block on a flat, frictionless surface. On one side is a spring connecting the block to a wall. On the other side, a person's hand is pushing the block towards the ...
0
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4answers
303 views

Why don't we take force proportional to velocity? [duplicate]

When a Force is applied on a body at rest, it produces Acceleration which is equal to change in Velocity. But due to the Force, we see that the Velocity is increasing consequently. So why don't we ...
0
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1answer
26 views

What forces cause the centripetal acceleration in circular motion on a merry-go-round?

Suppose you stand on a merry-go-round spinning at $f$ revolutions per second and you are $R$ meters from the center. What forces act on you? If you were tied to a rope like in Fig 2 you would follow ...
1
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2answers
96 views

Torque and Pulleys [closed]

I have the solution to the problem below, however I approached the question differently than my professor and I do not understand why my answer is different. Can someone help explain where I'm ...
0
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1answer
27 views

How is the load handled between a car and it's wheel?

I know, based on research, that the load of a car is transmitted to the wheels by properly torquing the lug nuts. I'd like to verify this through science. Alas, it's been a decade since I last ...
2
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4answers
72 views

What is the intuition behind “Net Work is Zero”?

I tried searching the answer to this all over the internet, but still cannot grasp this concept. So, when a book is being lifted, let's say $25 meters$ with a mass of $4kg$, with constant speed. I ...
1
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2answers
81 views

Ratio of the magnitude of the normal force to the magnitude of the gravitational force? [closed]

I'm working through some practice problems in preparation for my physics final and ran into one that I'm not sure how to do. A mass is released from rest from the edge of a large hemispherical, ...
1
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3answers
50 views

Force on a solid cylinder that is rolling on an accelerating block

Given: $m,R,I=mR^2/2, F,M$ and no traction between $B_2$ and the ground find $a_1, a_2$ (the accelerations of the CMs of $B_1$ and $B_2$ respectively).$B_1$ rolls on $B_2$ without sliding due to ...
3
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2answers
897 views

What is the cause for the validity of Newton's third law?

What, specifically, causes newton's third law? For instance, if I push on a wall, why is it that I experience a force in the opposite direction? I seem to vaguely understand that is has something ...
0
votes
1answer
53 views

Why does the water rise upwards when the bottle fall down with accleretion $>>g$?

When a medium-sized bottle filled with water quarterly falls from a height with acceleration $g$, the water remains calm. But when it falls with acceleration $>>g$, the water abruptly rises up ...
5
votes
7answers
3k views

Ball flying towards me or me flying towards ball

Suppose a ball is flying towards me at a speed of 10m/s and that, on impact, I feel "x" amount of pain. If, instead, it was me flying towards the ball at the same speed, with all other conditions ...
3
votes
1answer
31 views

Frictional force require to balance leaning sticks

Here is the question (from Morin's Introduction to Classical Mechanics book): One stick leans on another as shown in Fig. 2.21. A right angle is formed where they meet, and the right stick makes ...
1
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2answers
54 views

Pendulum's motion

Consider a pendulum in it's balance point hanging from ceiling. It can swing in all the directions in the space. The pendulum can only swing in a sphere(the string can't bend). Now, is it possible to ...
2
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3answers
68 views

Intuition and difference between centrifugal force & Coriolis force?

My book says that when a frame rotates uniformly, pseudo/fictitious force must be taken to count. This is centrifugal force. Also, while Googling, I found another pseudo force Coriolis force. ...
0
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2answers
38 views

Confused about Two Contradictory Facts

When an object hangs from the ceiling, through a rope, the tension force acts upwards, against the force of gravity. However, when a boy pulls a wagon, the tension force acts in the direction he is ...
0
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0answers
20 views

Inclined plane, circular motion and the friction

Suppose we have a cylinder on an inclined plane of mass $m$ and radius $R$ moving without sliding (so that $\varepsilon = a/R$). Why is the friction $F$ causing the circular motion sometimes lower ...
3
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3answers
143 views

What is the basic reason behind buoyancy?

Yesterday my friends and I were solving this easy-looking question: A metal cube is placed in an empty vessel. When water is filled in the vessel so that the cube is completely immersed in the ...
1
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2answers
76 views

Why do these two derivations of the formula for impulse contradict?

I was trying to derive $I = F\Delta T$ from $p = mv$. First I converted $v = at$: $$\begin{align} p &= mv \\ p &= m \times at \\ p &= ma \times t \\ p &= Ft \\ \Delta p &= F ...