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.
The question is regarding this image, I understand the two 50N forces provide a clockwise moment of 40 x 10^-2 x 100 which gives option D, as this moment must be balanced by the moment given by T.
Now my question is, how is the net force on this system equal to 0? It says it is in equilibrium...
TL;DR Summary: Forces on Elliptical Current Carying Loop
Please consider Current carrying elliptical 1-turn coil as shown in the picture.
Is it true that due to forces from the current , the elliptical shape of the coil will tend to become circular ?
Thank you...
My AP Physics notes state that counterclockwise is generally positive and clockwise is generally negative. This makes sense to me and means forces on opposite sides of the pivot point which act in opposite directions will work together, and this is the logic I applied to answer the problems...
Fx = 0 = ABcos(a)+BCcos(b)-BDcos(30)
Fy = 0 = ABsin(a)+BCsin(b)-BDsin(30)
==
Fx = 0 = ABcos(a) + 3.2737cos(b) - 3.738
Fy = 0 = ABsin(a) + 3.237sin(b) - 2.158
But i cant find a third equation to use. I've tried a+b = 90 but that produced a number of errors. Thank you.
Edit: angle b is the...
for 4kg box:
Fx = T
m1a=T
(4) (2.50) = T
10 = T
for 6 kg box: Fx = Fa - T
m2a = m2a - T
15 = 15 - T
15-15 = T
0 = T
I assumed the tension would be the same for both boxes, they are supposed to be, so what did I do wrong and is the answer 10 or zero?
So, my question is pertaining more to a specific part of this problem than actually calculating ##P## which I get to be ##P = \frac{kh}{2} - mg##. But I need ##P## in terms of a multiple of ##mg## so I need to find ##k##.
The solution attached uses the fact that when the object comes to a rest...
I found the internal force Vxy 25 +6 =31kn. , bending moment Mmin -qb2/2 , M min- 14 kNm. delta =M/W I can't find Mmax and tau= V/As. So I need help to find Mmax and As wall area, how to find.
In this problem why do I need to use this formula? F – F12 = m1 a along the x-axis. What does F12=-F21 stand for? And I don't understand when they say to find the magnitude of the forces between the two blocks
I think the first part is F = mxa? But given the jib is resting on a turntable at a certain distance, does that mean the longer and shorted ends experience different loads? Especially when the shorter end has a 16T counterweight?
The second part, I have no idea how to calculate this nor the...
I don't even know how to begin this. I know that I need to somehow account for the drag force that duck 3 is causing on the first 2, but I don't know how to deal with that. I am asking for someone to help me get started, not to give me the answer.
Hello,
Why isn't the forces resultant on a "large" molecule (by small molecule: water for example) zero? The reason for this Brownian motion is the thermal agitation of the water molecule. If we talk about white and Gaussian noise in electronics (due to the thermal agitation of the electrons)...
Frictions are neglected in the system pictured. Here, a 1kg object released from above moves the car underneath. When this object falls off the car, what is its speed in m/s?
This question was asked from momentum conservation, but I didn't want to do it from there. Can you solve the question...
Hi,
I had no problems calculating parts a and b, but I am having problems with task c
For ##F## I got the following, with ##\vec{r}= \left(\begin{array}{c} x \\\ y \\\ 0 \end{array}\right)## , ##\vec{r}_1= \left(\begin{array}{c} -a \\\ 0 \\\ 0 \end{array}\right)## and ##\vec{r}_2=...
Let the left string be T1 and the right string be T2. Pretend that the masses are NOT equal and that the total mass on the left is 3mg and the total mass on the right is 2mg.
My first thought: Net torque = 3mgR1-2mgR1
Actual solution: Net torque = (T1-T2)*R
Once again, the force that's used...
I was going through the stress-strain curve and I realized that strain is taken as the independent variable and stress as the dependent variable. In reality is this true or is it the other way around?I saw a lot of answers on Quora that say that strain is the cause and stress is the effect. But...
I've been trying really hard to calculate the forces between a permanent magnet that is within an electromagnetic field.
I have tried every formula under the sun, but it seems I am just not using the right ones, as my results always end up nonsensical.
To be clear, I am trying to understand the...
Hey all,
I'm either overthinking it or too tired but this problem should be an easy one to figure out but I'm stumped embarrassingly.
Say in the photo above is a lever arm. I'm trying to backtrack to calculate the force a user must input (yellow) against a force (red). It can pivot around...
I have difficulty understanding the extension of the fundamental laws of material point dynamics to systems.
Example 1:
Consider a system consisting of two material points. Suppose that the two forces acting on the two constitute a pair of forces of nonzero arm. The resultant of the forces...
While not exactly correct, we will continue to use Newtonian gravitational force and tension force in the lab frame. We will not concern ourselves with GR, besides the approximation is reasonable for low velocity and small mass.
In the lab frame, the forces acting on the pendulum is weight and...
The problem is based on a similar thread. In fact, the first question is extremely similar. However, the second question is the one I consider more interesting but I posted the first one too for context.
If this was just 1 pulley and two masses, then equilibrium is only possible if both masses...
Would it still work in a similar manner as an actual electroscope where you would charge it either positively or negatively and then observe attractive or repulsive forces or is there an easier and more efficient method?
There is an interesting paper by Arkani-Hamed and collaborators (https://arxiv.org/abs/1607.06821) to address the hierarchy problem.
There, they consider many possible models of fundamental particle physics where they all have an exact copy of the Standard Model but with different Higgs...
I found the answer for the springs in parallel, but not for the ones in series. I believe I don't understand how the forces are interacting properly.
Here's a force diagram I drew. Everytime I try to make equations from this though my answer dosen't make sense. The mass m has a gravititoanl...
The figure is shown below:
Here is my FBD for the figure with assign +x and +y directions
I started off by summing up the forces in the x-direction:
Next is the summing up of the forces in the y-direction:
After this, I solved for the moment at point A: assuming that counter-clockwise is +...
For a better understanding of this exercise here is the image illustrating the scenario described in the statement:
So to solve this exercise I began by drawing a forces diagram:
I believe I have explained everything in the "Relevant equations" section. What am I doing wrong? The book that...
TL;DR Summary: When a cube is supported at the fulcrum and remains stationary due to a balloon exerting a force in the opposite direction of its weight.
So the exercise is as follows: We have a homogeneous cube with an edge length of 2 meters, weighing 98N. On the other hand, we have a balloon...
Are forces subject to the Lorentz transformation? Not force carriers; I already got that question answered, thanks to @PeterDonis. But forces. The different forms of them, such as the contact forces etc.: https://en.wikipedia.org/wiki/Contact_force
With time dilation, does the rate of force...
Are there any limits to how fast forces can exert influence... or are they all instantaneous?
How fast are the forces of a collision?
I think frame dragging, with gravity, shows that at least gravity is not instantaneous, because if it is instantaneous, then how would it produce drag - it...
I've inserted a photo of the figure, hope everyone can see it.
SOLUTION:
1. I first solved for the angle of 100 N and 50 N since I need the force that is perpendicular to point A.
>> Angle of 100 N
theta = arctan(3/4)
theta = 36.870 degree
>> Angle of 50 N...
Hello PhysicsForums!
Here is my attempt at a solution for the problem stated above:
Where m1 and m2 are the masses
Where Ff1 and Ff2 are friction for each mass
Where a1 and a2 is the resulting acceleration
Where S is the fore of the wire (threadforce)
Where FN is the normal force
The answear...
Forces on rotating disk object
Hi. Is it convenient to ask following question.
Suppose we have solid circular object and 5 different moments
like in the picture:In moment 1 we apply force (downwars direction) so as to start rotating the object around center of
the mass (green dot) , Only...
If the dipole is to be in equilibrium at all positions as it's moved so that it's always inclined at 60° to the horizontal, then the torque due to electric field needs to be balanced by torque due to external forces ##F_{ext}## as shown in above diagrams. But such external forces will not make...
TL;DR Summary: Please Help. I need an answer for an Investigation
if a uniform bar of length 2200mm is supported evenly on 2 points (1 and 2) 1190mm apart. The bar is comprised of 3 sections (A, B and C) of varying masses. Section A and C have equal mass and volume and is comprised of the...
I am currently designing an alternative to normal acoustic drum lugs and I need to find the forces that are felt by the tuning rods of a drum for the engineering background to my design. I have been able to use the 2D wave equation assuming uniform tension on the membrane and found values of the...
Also, I wonder if a system can have work done to it due to its internal forces, as it is generally said that the work done due to internal forces is zero or at least I have learnt that(cannot trust my knowledge anymore, lol). I got this question in my mind because of a situation in another...
Hey everyone.
Let's say you have a tall tree. say, 10 m tall. Take a cubic cell 1mm in dimensions. Suppose the cell is at 1 m high in the center of the trunk of the tree.
What are the forces acting on the cell? let's say tree cell's mass is t grams.
its weight is F= ma = t (9.8) = 9.8 t...
This is how I interpreted the problem,
a) The net torque about point A is zero. This is because the forces F1 and F2 are equal and opposite, and they act at the same distance from point A. Therefore, they produce torques that cancel each other out..
The force F3 doesn’t does not produce any...
TL;DR Summary: Solar sytem forces on Unity
Hello !
For my last year in my school, I've got a project to do, and I wanted to recreate the Solar system with forces on Unity. My forces are Velocity and Acceleration (I'm using the Frenet's formulas).
I'm sorry I'm not a physicist and that's why...
The premise is that whenever you watch Battlebots or Robot Wars, there's usually a robot on there which has a vertical drum spinner which weighs half the robots weight and spins at thousands of RPM, and whenever the robot turns, it cocks one wheel in the air due to the gyroscopic forces at play...
Picture of problem:
For the object to be moving, it must overcome friction.
##f=0.5*0.6F = 0.3F##
##mg=22N##
Upward motion:
##0.8F>mg+f \rightarrow 0.5F>22 \rightarrow F>44N ##
Downward motion:
##0.8F+f<mg \rightarrow 1.1F<22 \rightarrow F<20N ##
I think correct option is D. Can you please...
neglect friction and motion (sliding) and G(sphere)=20N. In this question I reached two different result with two different solving method.But one of them is false according to answer key. My question is why first solving way is false? Because the first solution way makes sense to me. If we...
This might sound as a dumb and silly question but if you think about it, it makes sense. If we wrongly assume that gravity is a force just like any other, and given the fact that time is closely related to gravity and that gravitational time dilation is a thing, wouldn't reverse time travel...
Hello
I have alwayes seen FEM applications for static structures while each " finite element" of a bar linkage mechanisms should be subjected also to a variable inertial force besides its constant weight
how do FEM softwares compute inertial forces ?