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
18 views

Statics question: Calculate thrust force [on hold]

First and foremost can someone explain what is being asked here please?
-1
votes
1answer
9 views

Repulsive force between same charged plates?

I understand that the attraction force between parallel plates of capacitor is the derivative of stored energy with respect to distance of the plates. But how could we find the repulsive force between ...
-1
votes
1answer
30 views

Help understanding “Pushing blocks against headwind” [on hold]

I am new to StackExchange Physics so I apologize if I do any mistakes. I have been given a problem in dynamics and I have been working on it for a while but I am just getting nonsense. The problem ...
5
votes
3answers
111 views

Why would two protons repel?

I understand that two protons would repel due to them both being positively charged, however, wouldn't the strong force act on the two protons pulling them together? Would this mean that in this case ...
-1
votes
0answers
19 views

Calculate weight of one object suspended on a wire given angle of depression of wire and weight of another object [on hold]

Suppose I attach two objects to the left and right end of a sturdy wire whose folcrum is in the middle. The wire can't fall off. Using a horizontal line as my guide, I pull out a protractor and ...
0
votes
2answers
85 views

Thought Experiment: An object falling indefinitely under gravity?

So the other day, I devised this thought experiment: Consider an infinite tunnel, and you drop a coin of mass $m$ into it. Considering the effect of gravity to be applicable and neglecting air ...
-2
votes
1answer
32 views

Could you please help me find another example of motion under null net force? [on hold]

There are many familiar situations in which the net force on a body is zero and yet the body moves with a constant velocity. Here is one example: A car traveling at constant speed on a ...
0
votes
2answers
48 views

Fundamental origin of buoyancy force?

Generally, one can think of many different forces in daily life (normal, weight, friction, EM force, buoyancy, etc.). I can think of classifying them fundamentally as in each of the 4 major ...
1
vote
0answers
26 views

Calculating the torque required to move a heavy object (the calculations)

I wanna choose a motor for my bicycle and turn it into an electric one. So the physics part shoots. The force (Force=Mass x acceleration) that i will exert on earth surface(weight) will be my ...
5
votes
2answers
45 views

What factors influence the spring constant?

For certain springs we have been taught that Hookes law, $F=-kx$ works. For such springs, what factors determine k. For instance, k is proportional to length. Can k be expressed in terms of ...
1
vote
3answers
74 views

A problem related to Work done by falling bodies : Expert's attention much needed! [on hold]

I'm having a lot of trouble with this question, that I've found in my textbook. I've solved it in my own way and it's very simple! But the solution in the book is totally different. It doesn't make ...
-1
votes
1answer
53 views

Why do planets not stop revolving around the Sun? [duplicate]

Why do planets revolving around the Sun not stop revolving? Note I am not asking why planets do not collapse with Sun.
2
votes
2answers
44 views

Difference between adsorption and condensation

So I just stumbled across the Wikipedia article on adsorption - and I asked myself, if there is a difference between (physical) adsorption and condensation on a surface? When I look at the water ...
3
votes
2answers
62 views

What would be the photon's effective mass in Newton's Law of Gravitation?

If we equalize the force from the Newton's Law of Gravitation to Force on a photon in a gravitional field (I don't know if there is an equation for it). What would be the photon's effective mass? (I ...
0
votes
1answer
44 views

Why does Ampère's force only linearly depend on the distance between the two wires?

When we encountered Ampère's force law our professor stated: In the formula of the magnetic force you don't find $r^2$ as in the gravitational and the electric one because while those directly ...
1
vote
1answer
40 views

Does a force propagate instantaneously to move the other side of the box of length one light-year? [duplicate]

This is a question of curiosity, and not for any academic purposes. Suppose I push a box along a surface that allows it to slide. When I initially start pushing it on one side, how long does it take ...
-1
votes
2answers
51 views

Traveling to Mars in 24 Days

I am trying to calculate an electromagnetic rail launch from the Moon but I need to know if humans can survive the launch. Please see the specs below. 150 miles of track Proposed final launch speed ...
-2
votes
0answers
20 views

Men on the pully palte to lift [closed]

A plate has a fixed pulley. A men, standing on a plate pulls up with one end of the rope to try to lift the plate and himself; the other end of the rope is over the pulley to fixed on the ceiling, ...
1
vote
1answer
19 views

Is the buoyant force on an object is the reaction force?

Is the buoyant force on an object is the reaction force for the force exerted by the objects on the fluid (newtons third law)? Or there are two sets of action reaction force? (objects force and ...
0
votes
0answers
33 views

Two cars colliding with different speeds

If I have one car travelling at 30 m/s and another travelling at 10 m/s both weighing the same amount, why is it that the car travelling 10 m/s would have more damage? According to Newton's third law ...
0
votes
1answer
17 views

Circular motion normal force

Extracted from this article (see the bottom section): Some roller-coasters have loop-the-loop sections, where you travel in a vertical circle, so that you're upside-down at the top. To do this ...
2
votes
1answer
60 views

Am i trying to fly by pulling myself up by my hair? [closed]

I'm currently trying to build a multi-rotor of my own, and am testing it when i noticed that the lift that i am supposed to be getting is wayy less than what i am expecting. I have a rectangular body ...
-1
votes
3answers
76 views

Can a component of vector be greater than the vector itself?

...we have at our disposal an infinite variety of ways of resolving a given force into components. . . . The fact that any component may happen to be larger than the vector itself doesn't ...
0
votes
2answers
33 views

Calculating the flex of a solid bar under force

I want to calculate how much a solid bar will flex when force is applied to it. The set up looks like this: The rod (in green) rests on two stationary points, and the force is applied in the center ...
2
votes
1answer
198 views

Is force the derivative of energy?

In my lecture today my professor briefly mentioned that force is the derivative of energy but I did not really get what he meant by that. I tried to express it mathematically: ...
0
votes
1answer
34 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 ...
3
votes
1answer
55 views

Springs at an angle [closed]

I'm trying to find the equation of motion for the following system: This is how I proceeded: Let's call the length of the hypotenuse $s$. Then, $$F = 2 \sin{\theta}\cdot-k(s - l_o) = -2kx ...
1
vote
1answer
18 views

A particle collides with another particle in an (infinitesimally long?) elastic collision, what is the resultant force?

When an object collides with another object in an elastic collision, the first object exerts a force on the second object (and vice versa); how do you calculate the force that the object experiences? ...
0
votes
0answers
23 views

Finding the effective force constant in an accelerating frame [closed]

Consider problem #16 here: http://www.aapt.org/physicsteam/2013/upload/exam1-2012-unlocked-solutions.pdf Let me share my thoughts, and hopefully someone can tell me where I am going wrong. ...
2
votes
1answer
43 views

How much weight would I need to put on the end of a tube to break it?

Say I have a tube with a circular cross-section made from some material (for an example, I'd like to use acrylic). I support it horizontally from one end and hang a weight from the other end. How ...
6
votes
3answers
750 views

Why don't we consider jerk in physics classes? [duplicate]

When i got more into physics, i started asking myself if just like acceleration represents the growth of speed, something else could also represent the growth of acceleration itself. And it came that ...
0
votes
1answer
37 views

Force between two point dipoles

What would the force between two parallel point dipoles be? I was thinking of doing it the way force between two point charges is found out, by finding the field and then the force but I am not able ...
0
votes
0answers
55 views

Why golf balls travel faster if they spin?

From the book I have been given to read I found that balls spin due to the centripetal force but i am confused about how exactly do the resultant force causes it to spin and move forward about the ...
0
votes
4answers
58 views

Find the work done in moving an object along a vector r with a force F [closed]

$$r=3i+5j-2k$$ $$F=3i-3j+2k$$ What do I do. I know that work = force x distance. However, what vector operation should I do? I was wondering whether I should possible find the unit vector of r and ...
0
votes
1answer
30 views

Newton's 2nd and 3rd Law clarification [duplicate]

Hi I have a quick question. I know this may be a common question. If N3L states that there's an equal and opposite force, why do things still move? I have read up a lot and this is my understanding. ...
3
votes
6answers
962 views

Elevator cabin problem

The following passage is extracted from the book "Concepts of Physics, Part 1" by H C Verma: Let us consider the situation shown in figure. An elevator cabin falls down after the cable breaks. ...
3
votes
3answers
120 views

Why are forces independent from the frame of reference?

The following question occurred to me while reading a proof of the following statement: If K is an inertial frame of reference, then a K’ frame of reference, which is moving with a constant ...
0
votes
3answers
53 views

Newton's Second law of Rotation

In my book (Halliday Resnick Walker) there is a solved example which is as follows There is a uniform disk with mass $M$ = 2.5kg and radius $R$ = 20cm, mounted on a fixed horizontal axle. A block ...
0
votes
3answers
60 views

What force $\vec{F_{1}}$ is needed to balance the beam in the diagram below? [closed]

What force $\vec{F_{1}}$ is needed to balance the beam in the diagram below? I know that $\sum \vec{F}$ must equal zero. I also know that since the unknown force is farther from the pivot, ...
1
vote
1answer
36 views

Can gravitational force act as an impulsive force in any case? [closed]

Can gravitational force be termed as impulsive in any case? I' m thinking about it but couldn't get any answer. When two heavenly objects collide then the force exerted on each of them during the time ...
3
votes
3answers
1k views

How hard would I hit the ground on Mars?

How do you calculate with how much force a mass would hit the ground when falling from a certain height? In particular, I'm curious to know how the force of impact on Earth compares with Mars, so ...
28
votes
4answers
3k views

Stretch length of horizontal and vertical springs

If the spring in Figure A is stretched a distance d, how far will the spring in Figure B stretch? The spring constants are the same. The answer is "by half". I don't get it, to me it's the same.
1
vote
2answers
60 views

What role does static friction force play for a rolling object? How can I know what direction it points?

Fundamentally, what does a friction force do for a rolling object? I am very confused by the way my textbook explains it. In my textbook , it says: A wheel rolling on a horizontal flat surface at a ...
0
votes
1answer
23 views

Find angular velocity of motor

I'm quite bad at this, but I'm trying to change that and I need some assistance. Please bare with me while I attempt to explain what I'm trying to figure out and correct me where I'm wrong. Basically ...
3
votes
3answers
585 views

Is the shell theorem only an approximation?

I've read the shell theorem during gravitation lectures, i.e. I know it states that the net gravitational field inside a 3D spherical shell or a uniform 2D ring is zero. Now, assume a thin spherical ...
1
vote
1answer
140 views

Is gravitation really a conservative force?

A spinning gyroscope has a rigidity in space. That means it maintains its axis in relation to space – and not to the surface of the earth: Imagine a spinning gyroscope that is freely mounted in ...
-2
votes
1answer
54 views

Tension on strings holding a weight [closed]

It's a 100% standard problem in any basic physics course, and I cannot solve it. Here's the scenario: What is the tension in the strings (T1 and T2)? My thoughts were (cos/sin rewritten as ...
1
vote
1answer
45 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 ...
0
votes
0answers
27 views

Origin of the shape of the planets [duplicate]

Looking at our 8 planets over the years has left me a huge unanswered question. I know these planets compared to space is like a grain of sand on our entire planet. All the planets have the basic ...
0
votes
2answers
63 views

How does friction help the car to move forward? [duplicate]

Below is the extract from my book. There is a car with four wheel drive system and during acceleration, the engine causes the tires to push backward on the road surface. This push produces ...