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 ...

learn more… | top users | synonyms (1)

0
votes
0answers
41 views

Force conversion in a barrel cam-follower mechanism

A barrel cam-follower mechanism consists of a (cylindrical) barrel with a cam track, a cam-follower (roller) inside of the track, a fork connected to the cam-follower and a guide along which the fork ...
0
votes
2answers
64 views

Problems with work on an inclined plane

A constant force $F_a$ of magnitude $82.0N$ is applied to a $3.00 kg$ shoe box at angle $53.0^{\circ}$, causing the box to move up a frictionless ramp at constant speed. How much work is done on the ...
0
votes
2answers
53 views

How to determine the net velocity change applied by a force vector [closed]

I am a little stumped by the answer of this question. The question reads, "In three situations, a single force acts on a moving particle. Here are the velocities (at that instant) and the forces: ...
0
votes
0answers
59 views

Find the tension of rope A immediately after cutting rope B

As shown in the figure, a ball is attached to a ceiling and a wall with massless ropes A and B. Rope A is at angle θ from the vertical direction, and rope B is horizontal. The system is static. If ...
-1
votes
1answer
169 views

Why it's more difficult to walk in an inclined plane than in a causal road [closed]

my question is about something very casual , but when i tried to solve that , it was not easy at all . My question is : "Why when we walk in an inclined plane we get tired more than when we walk in ...
1
vote
2answers
49 views

Question about aircraft/rockets

Lets say that you're sitting an inverted airplane. How do you determine how fast the plane must accelerate in order for you to not fall out?
2
votes
0answers
97 views

Shouldn't there be 6 fundamental forces? [closed]

I'm listening to Leonard Susskind's The Black Hole War. In it he states (paraphrased) that a string wrapped around a compact dimension once imparts one unit of charge. Wrapped one way, it's a ...
0
votes
2answers
36 views

Why does limiting friction have to act when a block tied to a wall is pulled?

A block lying on a rough surface, is connected to a wall by a mass less, inextensible string and an unknown amount of force is applied to the block opposite to the side of the wall. Now, if it is ...
1
vote
1answer
32 views

Stuck on a static equilibrium problem [closed]

This is the problem: "The figure below shows a 25-foot sailboat. The mast is a uniform 119-kg pole that is supported on the deck and held fore and aft by wires as shown. The tension in the forestay ...
1
vote
3answers
61 views

Work energy theorem: variation of kinetic energy as sum of terms given by the work of single forces

Work-energy theorem states that $$W_{\sum F_i}=\Delta K,$$ where I expressed with $W_{\sum F_i}$ the work done by the resultant of forces ${\sum F_i}$ and with $K$ the kinetic energy. In general it ...
1
vote
2answers
49 views

Which side of liquid gas interface is at high pressure?

With respect to what(whether liquid or gas) should I consider that the convex side has higher pressure and concave at lower prsseure? As seen in the example of image it is given that air bubble inside ...
0
votes
1answer
32 views

Some questions about forces

If I am sitting inside a closed sphere (I can't see the outside), can't I feel when the sphere is at constant speed ? Can I feel when it is accelerating ? Why ? The defination of force given ...
0
votes
0answers
28 views

Determine what type of force that correspond to a springs-masses system

I am working a question from my Applied Math class, there is a question asked me to determine what kind of force correspond to a springs-masses system. I have two forces, $f_1=1$ and $f_2=-1$, spring ...
0
votes
1answer
27 views

Would a bullet damage a piece of metal the same as a pointy stick?

If you used a materials that would offer zero bending or dulling (the bullet/ pointy stick), would a 10 g bullet traveling at 1000 m/s with a surface area of 1 mm squared damage a piece of metal the ...
0
votes
0answers
28 views

can different force fields interfere (create interference patterns)

Edit: I have rewritten the question for clarity. I know waves of photons can interfere eachother. What about if you mixed waves of photos with w and z bosons? What about gravitons (if they exist) ...
0
votes
3answers
53 views

Pressure or confusion

We all know that pressure is force per unit area. for example we have a pressure of $5N/m^2$, so is the load of $5 N$ acts on the entire area or it acts just at a point i.e. is the load a point load ...
0
votes
2answers
119 views

Angular equilibrium on a see-saw

I have a tonne of questions related to see-saw equilibrium because most places I've been to online only deal with horizontal equilibrium - but static equilibrium can occur on an angle too. My ...
0
votes
1answer
43 views

Work done by a force

What is the difference between work done by a force and work done against that force? Is it true that work by a force = -(work against that force)?
1
vote
1answer
63 views

Work-energy theorem for a system

While studying energy conservation on Morin I found this explanation about the work-energy theorem for a system. The work–energy theorem stated before is relevant to one particle. What if we are ...
1
vote
1answer
67 views

Why do a conservative force try to reduce potential energy?

Mathematically I understood the reason why, for a conservative force, $\vec{F}=-\vec{\nabla}U$. Physically this means that a conservative force is always oriented in the direction of greatest ...
0
votes
2answers
78 views

Why does force cause acceleration?

Consider a ball placed on a smooth plane. If you take a plank made out of wood and whack it (apply a force on it), does it accelerate because First, the force compresses the part of the ball in ...
0
votes
0answers
63 views

Why is the longitudinal term removed to form the Lorentz force equation?

Beginning with the expression for interaction energy, and deriving the potentials form for the force on a test charge moving at velocity $\vec v$ yields: $$\vec F = q(-\nabla\phi - {D\vec A \over Dt})$...
-1
votes
1answer
38 views

The definition of the unit of Force

Below, I quote what my physics textbook says. $$F=kma$$ The units of force are so chosen that this constant of proportionality, $k=1$.Therefore $F=ma$. For this, one unit of force is defined ...
3
votes
1answer
46 views

Force and Torque

Think of a uniform sphere. Sometimes if a force is applied to the sphere it does not only move but also spins. So there is a torque. But is it possible to calculate which part of the applied force is ...
1
vote
2answers
56 views

Newton's law of gravitational attraction [closed]

My teacher would like us to use Newton's law of gravitational attraction to solve a question similar to this one: "Two objects exert a force of gravity of 20N. One object's mass is increased by a ...
3
votes
2answers
525 views

Is Newton second law covariant or invariant?

Is Newton second law covariant or invariant between two inertial frames, moving with uniform traslational motion with respect to each other? If it is invariant then, indipendently from the frame, $\...
1
vote
0answers
21 views

Kinetic energy vs Kinetic Energy scenario in a collision, mechanical energy used for work?

Most collisions have Kinetic energy conserved or in the case of inelastic collisions energy is lost into other forms. Though the equation of "TMEi + Wnc =TMEf" is true however, what if two unequal ...
1
vote
1answer
44 views

What component of the payload appears on the cross member? [closed]

I have a set of DIY steps; I've modelled it as the steps themselves "s", a short vertical support "a", a long vertical support "b" and a cross-member "c". Here's a picture: Just to be sure I ...
0
votes
0answers
39 views

Find the maximum force P that can be applied for which the blocks do not slide and their respective acceleration

Two blocks are on an inclined ramp of 35 degrees. Block A is on top of block B. Block A weighs 36 lbs and block B weighs 18 lbs. The coefficient of static friction between the two blocks is 0.45 but ...
0
votes
0answers
26 views

Linear thermal expansion from statistical mechanics?

I came across a question recently regarding work done by an expanding metal and the origin of the energy used for the work, and most of the responses pointed the person to look more at the enthalpy ...
0
votes
1answer
51 views

Working Out Shaft Torque in a Stirred Tank with a Cylindrical Cavern Formation (using a non Newtonian fluid)

Here is some background to the problem (in a stirred tank): "With yield stress non-Newtonian (viscoplastic) fluids, it is possible to generate an agitated volume around the impeller, defined as a ...
3
votes
3answers
204 views

Why is the definition of inertial mass circular?

On Wikipedia, the definition of inertial mass is: Inertial mass is the mass of an object measured by its resistance to acceleration. And, can be evaluated using $F = ma$, Newton's second law....
2
votes
4answers
108 views

Is torque necessary in rigid body mechanics? [duplicate]

Suppose we have a weightless, rigid rod fixed at one end, but free to swing at the other, where there is a mass $m$ attached. If we want to determine the tangential acceleration of the mass using ...
0
votes
0answers
21 views

Force by torque or force by speed with make the body jump?

I have a small object made of plastic weighing 3kg and I want to make it jump with the help of a dc motor and a plastic rod attached to it (4 such motor with rod are attached on the object at 4 ...
1
vote
4answers
99 views

Draw the Free Body Diagram

Question: Draw the Reaction Force at point P. My Attempt and Reasoning: Since the Reaction or the Normal Force is normal to the surface the solution according to me should be- However, the ...
0
votes
1answer
56 views

Related to pressure and force [closed]

If we made a thing like the one shown in the figure where the cross sectional areas of two piston heads are different and exposed to the same atmospheric pressure and the air between the piston heads ...
4
votes
3answers
118 views

If neutrons aren't affected by electromagnetic force, what causes it to bounce off matter?

Say a neutron is heading for a mountain, what would cause it to bounce off said amalgamation of matter? Electromagnetism is ruled out, gravity is too weak, (if I'm not mistaken) nuclear strong force ...
4
votes
4answers
320 views

Why do wheels spin?

I'm pretty sure this is probably a stupid question but it is annoying me a lot. In my physics textbook it says, cars move because the wheels exert a backward force on the ground and the ground exerts ...
1
vote
2answers
96 views

Why is the restoring force directly proportional to extension?

When deforming any spring the deforming force is always greater than the restoring force until equilibrium is reached. So, if a constant deforming force caused an extension in any spring the restoring ...
1
vote
1answer
32 views

Why isn't the entire force we apply on two objects transmitted to the second object?

When we exert a force of X N on a box in contact with another identical box on a frictionless surface, the resultant force on both boxes is 0.5X N. My question is, why doesn't the first box push the ...
1
vote
2answers
61 views

Rising glass in xkcd what if

In http://what-if.xkcd.com/6/, Around this time, the glass on the left starts to visibly lift into the air. The air pressure is trying to squeeze the glass and water together. This is the ...
1
vote
3answers
80 views

Why do objects with mass have gravitational force that is proportional to their mass?

Why do objects with mass have gravitational force that is proportional to their mass, i.e the larger the object the more gravitational force it has?
0
votes
1answer
39 views

Basic tension and equilibrium confusion

The following is what I did: $$Fsin\theta = 60 => F = 93 N$$ $$Fcos\theta = 40 => F = 52 N$$ Why do I get different results? Does this mean the object isn't in equilibrium? How can I proceed ...
0
votes
0answers
39 views

Force on a charge due to charged sheet

I want to find the force on a positive charge placed at a distance $d$ from a positively charged infinite plate. Of course, it can simply be done by finding the electric field due the plate using ...
6
votes
4answers
96 views

Newton third law and collinearity of forces

I have a doubt on the formulation of Newton third law. When one body exerts a force on a second body, the second body simultaneously exerts a force equal in magnitude and opposite in direction ...
0
votes
1answer
72 views

How to model analytical expression for spring constant $k$ for certain structure?

In the deflection of beam, I learned that $$ \delta y=\frac{FL^3}{3EI} $$ where $$ I=\frac{h^3w}{12} $$ Together they comprise $$ F=\frac{Eh^3w}{4L^3}\delta y $$ How do I apply to four beams? is ...
1
vote
0answers
19 views

How to measure the properties of a non-newtonian fluid?

We have made non-newtonian fluid by mixing water (or Tonic) and starch. We can't figure out the link between the amount of water and starch and the viscosity of the fluid. What we can figure out is ...
1
vote
0answers
31 views

Superstring mass between 2 D-branes

The mass of a superstring between 2 parallel D-branes of dimension $p$ and $q$ is $$m^2=(N−a)+(y/2π)^2$$ But what is the value of the normal ordering constant $a$?
1
vote
1answer
29 views

Forces & Pressure

So, today I learnt that P=F/A. For something with a flat surface, it is easy to grab. Then came to my mind, how about the pressure exerted by a curved surface? How do you calculate the pressure? To ...
0
votes
2answers
48 views

Helium Lift Potential [closed]

A particular mass of helium is required to lift a particular weight. If the weight stays the same and the mass of helium is decreased can the same lift force be achieved by increasing the ...