In physics, a force is any influence that, when unopposed, will change the motion of an object. A force can cause an object with mass to change its velocity (which includes to begin moving from a state of rest), i.e., to accelerate. Force can also be described intuitively as a push or a pull. A force has both magnitude and direction, making it a vector quantity. It is measured in the SI unit of newton (N). Force is represented by the symbol F (formerly P).
The original form of Newton's second law states that the net force acting upon an object is equal to the rate at which its momentum changes with time. If the mass of the object is constant, this law implies that the acceleration of an object is directly proportional to the net force acting on the object, is in the direction of the net force, and is inversely proportional to the mass of the object.
Concepts related to force include: thrust, which increases the velocity of an object; drag, which decreases the velocity of an object; and torque, which produces changes in rotational speed of an object. In an extended body, each part usually applies forces on the adjacent parts; the distribution of such forces through the body is the internal mechanical stress. Such internal mechanical stresses cause no acceleration of that body as the forces balance one another. Pressure, the distribution of many small forces applied over an area of a body, is a simple type of stress that if unbalanced can cause the body to accelerate. Stress usually causes deformation of solid materials, or flow in fluids.
What happens if I have a permanent magnet outside an ideal solenoid? Does the permanent magnet rotate until the system reaches an energy minimum in its magnetic fields? Or does the permanent magnet fail to rotate because the magnetic field of the solenoid does not reach the magnet? Wouldn't...
I have been reading many examples of control volume calculations regarding nozzles
They all end up with a reaction force on the nozzle in the direction of the flow.
I can't understand this from a Conservation of momentum perspective.
I would expect that the reaction force, by Newtons third...
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A pith ball is charged by contact with a Van De Graaff machine, and is repelled away from the dome. It remains at its location. Using the chart given, what is the mass of the pith ball?
Distance between centre of generator and pith ball...
gluons can form glueballs, and glueballs can have spin-0 and spin-2
as a composite boson of spin-2, does it mediate new forces/interactions, and would a spin-2 glueball always be attractive the way gravitons are?
do spin-0 glueballs form a condensate similar to the higgs field?
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HELP! L-shaped tank problem! figure: http://www.webassign.net/hrw/hrw7_14-33.gif
The L-shaped tank shown below is filled with water and is open at the top.
(a) If d = 7.0 m, what is the force on face A due to the water?
(b) What is the force on face B due to the water...
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Two parallel wires have currents passed through them which are in the same direction. Draw a diagram showing the directions of the currents and of the forces on the wires.
Alternating currents are now passed through the wires. Explain what forces would act if the currents...
Two questions I had:
1. How is the force of friction of the tires pointed inwards to cause centripetal acceleration? If the tire is rotated when trying to turn, the car is still traveling with a velocity perpendicular to the circle and force of friction would still be counteracting the...
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An 8.5 gram slug is fired East from a 0.357 magnum hand gun held 1.5 meters above the ground. The muzzle velocity (as the projectile leaves the gun) is 1400 ft/sec. The bullet is accelerated at a constant rate as it travels through the 10 cm long barrel. After leaving the...
In relation to two objects with a gravitational field on them (i.e. a planet and its moon), would there be two pairs of partner forces (the force of gravity exerted from each object and the resulting partner force from each force of gravity)? For example with the Earth and moon:
1. Force of...
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Homework EquationsThe Attempt at a Solution
I'm having trouble coming up with the equations for the system. At first, I thought that m2 = m1sin(theta), but that's not correct. How can I set this problem up?
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On a farm, you are pushing on a stubborn pig with a constant horizontal force with magnitude 34.1 N and direction 37.0∘counterclockwise from the +x-axis.
a) How much work does this force do during a displacement of the pig that is s⃗ =(5.00m)ι^?
b) How much work does this...
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In this experiment, a suspended metre-ruler lies in a series of equilibrium under non-parallel forces.
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The apparatus consists of the following. A metre rule suspended by strings which make an angle with the vertical. The strings run over pulleys which are...
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I have a man who is 100kg and a barrel of bricks weighing at 220kg. The man is using a pulley to lower the bricks onto the ground however since they are much higher in weight he rapidly travels up. Then the bricks fall onto the ground and the barrel weighs 60kg since it's...
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At a construction site, a small crane is raising two boxes of nails on a plank to the roof. One box has already been opened and is half full, while the other box is new. The boxes, including the nails weigh 10kg and 20kg, respectively, and are the same size.
If the...
If one fires a pistol while holding it in one's hand, the pistol will exert a backwards force above the grip of the hand, causing the gun to both move backwards as well as exerting a torque, as the hand is essentially behaving as a fulcrum. If a pistol is fired in a gravity-free environment with...
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Two rods of the same material, of equal length l, and of cross section A and 2A respectively, are mounted between two rigid (i.e., nondeformable) cross frames. The frames are pulled by a pair of forces P, located at distance x from the thin bar. Derive an expression for the...
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sam makes a punch hole with the perforater( two holes ). She presses the lever at A down with a force of 40 N. Calculate the total force which a single pin presses on the paper.
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http://s6.postimg.org/yx62wbild/image.png
The Attempt at a Solution
would it...
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Can someone please help me with this A level physics question on Mechanics.
Help will be appreciated. The picture of question is attached. :D
Thank you
Homework EquationsThe Attempt at a Solution
[/B]sin20x590=201.79N or cos70x590=201.79N
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A positive point charge Q_1 (4.0 µC) and a negative point charge Q_2 are placed near each other. When a negative charge Q is placed in the middle between the two point charges, the magnitude of the resultant forces on Q_1 and Q_2 doubles. What is the charge of Q?
(answer...
So I've been given this practice problem for a test tomorrow and have no clue how to do it.
Info: Students Perform a lab and record data on how changes in mass affect acceleration
"Derive an equation that you graph to make a linear relationship from the recorded data."
Given is a data table...
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Hello, this problem is cracking my mind for days, and I haven't solved it yet :(
Crane dimensions: See image
Mass of the crane: 10Tons
Mass center: G
Maximum Load: 4Tons
Counterweight: P
Weight of the counterweight: ?
"A" says: when you have a maximum load (4Tons) at the...
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Determine the smallest force P that will cause the spool to have impending motion.
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Equations of equilibrium, and static frictional equations.
##ΣFx = 0;##
##ΣFy = 0;##
##ΣMb = 0;##
##Fsa = μNa##
##Fsb = μNb##
The Attempt at a Solution
My first...
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Determine the moment about point B of each of the three forces acting on the beam. Homework Equations
M = F*d⊥
The Attempt at a Solution
I went and found the components for each of the forces. Please double check it if I did them right:
F1 :
Fx = 0
Fy = 375 lb
F2:
Fx...
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the main question asks: "If the book is initially at rest, what is its speed after it has traveled 0.400 m up the wall?"
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∑F = m*a
vf2 = vi2 + 2 * a * d , when initial velocity is 0.
The Attempt at a Solution
So here's my free body diagram:
and out of...
I'm very new to physics and am doing a crash higher course. I am currently tackling dynamics, and here is one of the questions I was given.
8 ) A car of mass 800kg is accelerated from rest to 18m/s in 12 seconds.
a) What is the size of the resultant force acting on the car
b) How far does it...
Consider a free-falling object with known mass and center of mass being acted upon by four forces -- force of gravity at the center of mass, as well as three additional force vectors applied at known positions on the body. Is it possible to calculate, in closed form, the position and...
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Determine the magnitude of the resultant forces and direction of the resultant as measured clockwise from the positive x axis.
Homework EquationsThe Attempt at a Solution
Please help. I have entered my answers into masteringengineering.com and it keeps telling me my answers...
in broken supersymmetry every fermion has a super partner that is a boson, with same internal quantum numbers, except mass. i.e superpartner of an electron is a selectron, which is a boson.
in QFT gauge bosons are force carriers. gauge bosons with mass create a force that is short-ranged...
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Hello, I have attached a physics problem that I solved yet some answers (in red+the first answer) are wrong and I can't find out why...
Homework Equations [/B]The Attempt at a Solution
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A chain of mass M and length L is suspended vertically with its lowest end touching a scale. The chain is released and falls onto the scale. What is the reading of the scale when a length of chain, x , has fallen? (Neglect the size of individual links.)
Homework Equations...
Looking for some help with a rear brake caliper design.
The rear caliper bolts to a carrier that slides onto and rotates around an axle. An torque arm (motorcycle term) or brake stay is required to prevent the caliper from rotating when the rear brake is applied.
I have to figure a way to...
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Homework Equations
T = 2π√(m/k)
mx'' + kx = 0
F = ma
The Attempt at a Solution
I don't honestly know where to start with this. I'm really out of my league in this class, and I'm trying my best to catch up with the things I didn't quite master in Dynamics and Physics...
As...
So sorry to post what seems to be a well worn question. So the 4 forces of nature work by "particle exchange" ? Yes we understand the maths of "Fields" and we have the elegance of Maxwell and Newton/Einstein and these mathematical descriptions lead us to force exchange particles which can...
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Find height (h) of the water level which can result in failure of dam by tipping it over due to water pressure at U/S of dam. Also draw the free body diagram.
Density of water to be = 1000 kg/m^3 and its specific weight=62.4 lb/ft^3
Hints: The specific weight of concrete is...
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Centripetal acceleration$$=\omega ^2R$$
Coriolis acceleration $$=2v_{rot}\omega $$
The Attempt at a Solution
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Think of the mass as lying on an incline. The forces I know are parallel to the incline are $$mgsin(\alpha), \mu N$$
Forces I know are...
Alright, I feel this may be a pretty basic question, but I have not gotten a satisfying answer yet. I'm taking Electromagnetism right now and I got to thinking: how do fields physically interact? What I mean by this is, on a subatomic level, a field can create a force on another particle or...
Why is it so that the net work done by a force on an object is equal to change in kinetic energy only and not any other form of energy like potential energy? Also is the work energy theorem valid for both conservative and non conservative forces.
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Each one of the force vectors are surrounded with dimensions. But you're not given any angles. How do you solve for the resultant vector like that?
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Fr = F1 + F2 + F3 The Attempt at a Solution
I tried taking the arctan(200/210) on the 435 N vector to...
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Explain why the velocity at time of impact was much higher than the average velocity
Explain why the actual gravitational potential energy will in reality be much higher than this
Explain why increasing the time of impact would mean the rocket was less likely to get...
How do conservative forces exactly conserve mechanical energy while non conservative forces do not. Also why is potential energy defined only for conservative forces?
Let me start by saying that I'm a physics student but I have no experience with GR other than some pop-sci and some clarifications on that pop-sci from various sources, so basically I'm saying that some math is fine but please bare in mind that I have no real experience with the relevant math...
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Hi, this is not really an academic homework but it is something I'm trying to solve for my future project. I have a background in electrical engineering hence I'm having a hard time solving the forces problem.
https://dl.dropboxusercontent.com/u/43124243/Force_problem.png...
Hello Gurus,
What are the forces opposing rotary motion? And how to calculate them?
For eg., if we have a shaft rotating about it's own axis, are there any other forces that oppose this motion other than bearing friction, like air resistance or some other forces. And how to calculate these...
Hello Forum,
I am revisiting Archimedes principle and its important consequences.
I am aware that a cube (homogeneous) made of iron will always sink in water regardless of its mass. If we changed the iron cube into a different shape (cone, cylinder, prism, parallelepiped, etc.), the object...
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Homework Equations
The Attempt at a Solution
I have spent the last 2 hours trying to figure out which part of the truss is compression or tension. Hopefully the second screenshot I took is correct. I tried figuring out the first few parts, just want to make sure that at...
Just wondering about energy. I find energy and fields the 2 most fascinating parts of physics. Since potential and kinetic energy are functions of gravity (and perhaps other forces I hadn't considered); are all types of energy functions of a force? Or are there also exceptions? Or unknowns...
Well First of all, I noticed tons of thread about this in the forums and tons of the same question being asked in all kind of scientific forums. I am pretty sure everyone here hates this topic, and I have got a bad headache from reading all the comments, but just clarify this to me.
"Most of...
I am trying to understand what forces keep a free vortex, (i.e. a vortex ring). Its rotating particles must have a force to avoid them going out (like gravity on planets). I have read about vortices and vorticity, but get lost in equations.
Is it possible to explain the force that keep the...
If an object say a cylindrical body is gripped in a frame and that frame is being rotated by some mechanism, what forces should be considered on the gripped object in order to know the necessary force required for a proper grip?
Please have a look at the diagram. The black circle represents a motor, the green circle represents the rotating shaft of the motor, and the red beam is attached to the motor's shaft. The motor spins the red beam counter clockwise in the direction of the arrows.
What I need to know is how to...