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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2
votes
0answers
11 views

How to determine the overturning moment on a stand alone, uncovered bean pole tipi

I will preface this by saying I am a highschool student who has not yet had a physics class. I engineered and built a hexagonal shaped, open bottomed, planter to hold soil that would contain pole ...
2
votes
3answers
61 views

Why does weight on Earth have a tangential component?

I read in Pulsar's answer of this question that weight has a tangential component due to the rotation of the (assumed spherical) Earth but I don't understand this. Can someone expand on it please?
0
votes
1answer
21 views

Electric Potential produced by Hollow Sphere

Let there be a hollow sphere (Throughout the question we will ignore the thickness of the sphere) which is positively uniformly charged,q of radius, R. Suppose there to be a test positive charge, q' ...
0
votes
1answer
1k views

Understanding the math behind a falling object attached to a parachute

I'm trying to understand the mathematics behind calculating the total speed and force of a $40 kg_f$ object hooked up to a parachute, falling to Earth. From what I understand, the formula for this is ...
0
votes
1answer
22 views

Weight Detection Under Concrete/Asphalt

Consider that a weight sensor was embedded in a road. Would cars that drive over it trigger the sensor? I was thinking it'd look something like this (if we ignored the downward force that the ...
-2
votes
0answers
17 views

Multi Car collision [on hold]

If a 2.8k lb car impacts with a 5k lb truck at an angle that lifts the back of the truck (impact at 25mph), would the truck be able to push 3 cars weighing at 3k, 5k, and 3.5k forward 20 ft when ...
52
votes
6answers
7k views

Why is the Moon considered the major cause of tides, even though it is weaker than the Sun?

You have likely read in books that tides are mainly caused by the Moon. When the Moon is high in the sky, it pulls the water on the Earth upward and a high-tide happens. There is some similar effect ...
-5
votes
1answer
43 views

Newton's 1st law [on hold]

If all of a sudden the gravitational force and gravity disappears then the planets would still continue to rotate and revolve ? Give reason
1
vote
0answers
82 views

Friction to just move the blocks

Two blocks each of mass $m$ are placed on a rough horizontal surface and connected by mass-less in-extensible string as shown.The coefficient of friction between each block and ground is $\mu$ What ...
-1
votes
2answers
136 views

What would happen to a motor without a split-ring commutator?

I realise that a similar question has already been asked (Why does the coil in this apparatus reverse its direction of oscillation?), however after reading the answers, I am still unclear on certain ...
5
votes
3answers
1k views

Has a body angular momentum and torque only in a circular path?

In different contexts, my book(Principles of Physics by Resnick, Halliday ,Walker) , they wrote For torque, the path need no longer be a circle and we must write the torque as a vector $\vec{\tau}...
1
vote
2answers
182 views

If I double the amount of oxygen molecules, do I double the paramagnetic force?

Oxygen is well known to be paramagnetic. If I take one molecule, $O_2$, and measure its paramagnetic force due to externally applied magnetic field, and then add another molecule near the first ...
0
votes
3answers
161 views

Does the work done by a person equal the work done on the object in this situation?

If you applied a constant force over a floor that has friction on an object, would the work done by the person equal to the work done on the object? Assume that the floor is flat and that the object ...
0
votes
0answers
58 views

In the equation $F = kma$ , what's $k$? [duplicate]

Actually I want to know that what is $k$ & why it's SI unit is set to 1. Also if it's can be expressed in SI units , that means it can be converted into CGS etc. units .. So what's the value of $k$...
1
vote
1answer
219 views

Can two bodies of different mass attached at ends of string passed over a frictionless pulley produce equal tension on both sides?

In my textbook there is given a case that to calculate acceleration and tension produced in string when string is attached at it's ends with two bodies of masses such that $m1>m2$ and the tension ...
0
votes
0answers
30 views

Free Body diagram force question

Here is a semicircular track and the ring of mass $m$ sliding on it. The ring is attached to spring of force constant $k$ and the elongation $x$ at that point.I just wanted to know that just as I ...
0
votes
0answers
33 views

Acceleration mass graph of constant force

If the same horizontal force is applied to objects of different mass. Which graph explains the experimental results. My logic was that since $$ f = ma $$ Is a linear equation it will be a straight ...
-1
votes
1answer
35 views

How would you go about solving this graphical mass problem? [on hold]

I've tried finding the x and y components of the vectors created by each mass to find the resulting vector's magnitude. However, my answer of 0.354 N keeps getting marked wrong. Any ideas on how to ...
2
votes
0answers
64 views

Confusion in reaction force of Ampere's Force Law [on hold]

I am reading Maxwell's "A Treatise on Electricity and Magnetism" and I have some confusion in the following pages: The element ds is resolved into its components $\alpha$ and $\beta$;and the ...
0
votes
2answers
41 views

Pendulum force components at maximum displacement

If $\theta$ is the maximum angle for the pendulum's swing, then should $T\cos\theta=mg$ or should $T=mg\cos\theta$. I think that the components must be done in the perpendicular directions $T\cos\...
0
votes
1answer
41 views

If the applied force is constant, what is the graph of the velocity?

This is a sample interview question from Oxford: A ball, initially at rest, is pushed upwards by a constant force for a certain amount of time. Sketch the velocity of the ball as a function of ...
0
votes
2answers
56 views

If photons mediate EM force? How can they tell to be attracting? [duplicate]

Like a photon is neutral, when a proton say feels a push from another proton, how does the proton know it was a proton pushing it and not an electron pulling it? Im not asking how the details work of ...
0
votes
2answers
64 views

Why is the magnetic force not (never) in the opposite direction

In this question I'm talking about the left-handed orientation for the direction of the $x$, $y$ and $z$-axis. This is the coordinate system at the left of the picture below. I learnt that when you ...
0
votes
0answers
34 views

Calculate displacement of one body connected to an other by spring and forced in a direction [on hold]

Two bodies of mass $M_1$ and $M_2$ are connected by a spring but are otherwise free to move along a horizontal line. A periodic force $F\cos\omega t$ is exerted on the body of mass $M_1$ along the ...
0
votes
0answers
20 views

Deriving coulomb's law [on hold]

Suppose you had two charges Q1 and Q2 a distance x away from eachother. I've been asked, given the equation for the potential energy between the two, to derive for force law for this (I'm not 100% ...
0
votes
1answer
19 views

Charge density on two hemispheres, enclosing a conducting sphere [on hold]

Two uniformly charged non conducting hemispherical shells each having uniform charge density $\sigma$ and radius $R$ form a complete sphere (not stuck together) and surround a concentric spherical ...
1
vote
1answer
401 views

Force of a solenoid on a ferromagnetic material

As I was trying to find an answer to another problem, I was informed that the equation I was using would not work. The equation I was using was $$F = (NI)^2\mu_0\frac{\text{Area}}{2g^2}$$ If this ...
0
votes
0answers
10 views

Charpy problem, Impact velocity [on hold]

Calculate the velocity of the hammer of an impact testing device at its lowest position if the hammer starts moving at an angle 30° to the horizontal (mass of rod=0.5kg, length of rod 400mm. mass of ...
0
votes
3answers
56 views

Tension in a string with pulley and two objects at opposite ends

Tension is confusing me. According to my understanding of tension the tension in a string is uniform but while going through the solution of a problem I read that tge tension on the left part of the ...
0
votes
1answer
71 views

Point charge inside a electrically neutral cavity in conductor placed eccentrically, and effect of external electric field if switched on

bear with me, but i would like a definite answer, now, starting off the external charge density on the outer surface of sphere WILL be uniform by unique solution of Laplace equation and letting the ...
18
votes
3answers
2k views

Gravitational force when standing on an infinite disc

If a person were to stand on a flat disc of thickness 1 meter but infinite diameter, would they experience finite or infinite downward force? There is an infinite amount of mass, all of which ...
2
votes
1answer
40 views

Cable wakeboard raley

Illustration of the problem: http://www.youtube.com/watch?v=OWRixptJaRo The non physics solution: http://www.youtube.com/watch?v=FRwHcJjfCR4 My first approach to learn this was to follow youtube ...
1
vote
2answers
48 views

Force of water hitting a wall [on hold]

If you had a 8" pipe with 500psi stream of water exiting it and hitting a wall at 90 degrees 8 feet away, what would the force of the water on the wall be? Thank you all. Non-mathematician.
3
votes
2answers
1k views

Average Force vs Net Force

The F in $$Impulse = F*t$$ is said to be the average force. For a ball dropped vertically onto a horizontal surface, the average force, F, on the ball from the floor is: $$F = \frac{\Delta{p}}{t}$$ $$\...
3
votes
2answers
22 views

Why is the damping force acting on an oscillating system opposite in direction to velocity and not acceleration?

So far I know that the damping force is a frictional force that opposes motion and so it acts in the opposite direction to velocity . Bit why can't the same be said for acceleration doesn't the ...
1
vote
2answers
42 views

How well-defined is the infinite-sheet-of-mass computation?

When computing the gravitational force from an infinite plane (or the electrical field from an infinite sheet of charge), it is standard to begin by making a symmetry argument to say that the ...
13
votes
3answers
691 views

Infinite grid of planets with Newtonian gravity

Assuming only Newtonian gravity, suppose that the universe consists of an infinite number of uniform planets, uniformly distributed in a two-dimensional grid infinite in both directions and not moving ...
0
votes
3answers
2k views

How do suction cups work?

My roommate and I are having trouble agreeing on how suction cups work. Presumably, the ambient air pressure is the only thing which keeps the suction cup attached to the object. When lifting an ...
1
vote
1answer
298 views

Question on Binet's equation

Is there a difference in Binet's equation when the force acting on a body is attractive and repulsive? I mean, if the force has a magnitude $F(r)$, is it Binet's equation always $$\frac{d^2u}{d\...
0
votes
1answer
96 views

Expressing virtual force in terms of muscle contraction force

Two bodies connected with a hinge joint with axis in J. They also connected with a muscle at points M and M`. I’m trying to express virtual force Fv in terms of muscle force Fm acting at the point M ...
0
votes
2answers
31 views

Work and energy example [duplicate]

The normal definition of Work, as far as I have read, is: Energy is transferred through work. But I just heard an educationist state this example, where there is a weightlifter who keeps up a huge ...
0
votes
1answer
88 views

Sliding blocks problem

My first post here, so I apologize if this is duplicated elsewhere. It IS a "homework" problem, but it's public domain, a posted exam with answers... http://www.mun.ca/physics/undergraduates/...
0
votes
2answers
103 views

Work energy theorem explanation

So there is this problem in my head, it may seem very simple, but I need an answer. The problem is, we have some object, and we apply a force by our hands with a constant speed from a position (1) to ...
0
votes
2answers
56 views

Why there is an extra componet of force in this Equilibrium state?

I have a question about the forces on a body at equilibrium. Look to this image: here i draw a man standing with a pen on earth. And I think that I draw all possible forces on it. They are as ...
0
votes
2answers
875 views

Can we make a force which can oppose earth gravity? [duplicate]

If we are standing on earth, then some force (gravity of earth) is pulling us down. Can't we make a force which can oppose gravity? Can't we make an object of zero mass?
2
votes
2answers
209 views

Balancing forces on a liquid [closed]

My reasoning is as follows Atmospheric pressure = $P_{0}$; Spring stretch = $x$; Pressure under top piston = $P$ Balancing forces on top piston $kx + P S_1 = P_0 S_1$ Balancing forces on bottom piston ...
0
votes
4answers
45 views

Force needed to flip/overturn object [closed]

I can't find a way to solve this physics problem: I have an l-shaped object (Mass: 10KG and edge of length a) on a surface and I need to calculate the force needed (applied on the top right corner,...
0
votes
0answers
15 views

How does Torque from tidal forces scale with distance

I read in a paper a while back that the torque on a body caused by differential rotation and tidal forces scaled with distance to the power of 6. That struck me as odd since the tidal force scales ...
-1
votes
0answers
52 views

What prevents the ball from falling down? [closed]

A person runs on level ground as they hold on to a string. At the end of the string is a ball. The ball stays floating in the air. There is tension in the string pointing sideways, and gravity acts ...
3
votes
1answer
2k views

Why does the beam in a weighing balance get tilted proportional to the weights added to each pan?

I'm talking about a beam balance(a simple weighing balance with a beam and two pans hung on either side) As answered in a previous question, the beam comes back to the original position when one ...