New answers tagged forces
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2 objects heading towards each other at a certain distance and with initial velocity and friction coefficient
Depending on the mass of both A and B (assuming the friction is caused by a gravitational force), the answer will change.
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Does the acceleration formula from dynamics apply in all cases?
Acceleration is total external force divided by mass provided the object in question can be treated as a point mass with a single acceleration and it is not moving so fast that relativistic ...
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Why does a plastic bag rip when it is raised to a higher position when being held but not when it is stationary?
You move the bag upwards with an acceleration. If you were to pull the bag up with infinitesimal acceleration, it would not rip then, because the force required for that would approach zero. But since ...
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Why does a plastic bag rip when it is raised to a higher position when being held but not when it is stationary?
This is like holding a weight $mg$ with a string which can break with a tension of $1.1 mg$. When you are not moving the bag, or moving it at a uniform speed, the string's tension is constant at $mg$,...
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Centripetal Force Formula Confusion
You are trying to think of the force in terms of radius, whereas the force required depends upon both the radius and the linear velocity V or angular velocity. Try to think about how much minimum ...
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Force as a Function of Position
dont make things so complicated: m(dv/dt)=F...then multiple both sides by v(dt), we get mv(dv)=Fv(dt)...because vdt=dx....then mv(dv)=F(x^0)(dx)...intergrate...and you find K.E.=P.E., or force as a ...
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Vertical component of moving weight at a 45 degree angle
While the technically correct answer is W × sin(45), practically I think the ratio is closer to
0.5-0.6. Due to the balance necessary in an unbraced squat with a ...
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What is the constant in $F=kma$ called?
Closest analog to your expression would be relativistic Newton second law :
$$ F = \gamma ma \tag 1,$$
where $$\gamma = \frac{1}{\sqrt{1-\frac{v^2}{c^2}}} \tag 2$$
is called Lorentz factor, but it's ...
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Direction of undetermined contact force & undetermined Normal force
In a situation where two corners are in contact, the contact force (acting on the blue part below) can be in any direction (and magnitude) and thus can be decomposed into two components.
In a ...
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Bar suspended by three vertical ropes
This is a canonical example of an underdefined problem (the number of unknowns (3 tensions) is less than the number of conditions (torque=0 and total force=0). You've tried to come up with a third ...
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How does friction applied to a rolling sphere in 3 dimensional space
The plane is described with u , v parameter and the trajectory on the plane with s parameter . Thus the position vector to the contact point is
$$ \vec R=[x(u(s),v(s)), y (u(s),v(s)),z (u(s),v(s))]^T$$...
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Rotational Equilibrium With Forces acting on only two points
The rod cannot achieve rotational equilibrium. Your thinking is right.
The rod will have to rotate about the hinge because of the torque due to its weight.
mgsinθL/2 = Iα
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Why can multiple eggs support more weight per egg when there are more of them?
Because the pressure changes and the weight is distributed to each egg.What causes fracture or any other plastic deformation is pressure not force.
Pressure $P$ is related to force $F$ by this formula:...
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Can two electrons attract each other?
We are currently exploring a hypothesis that suggests two electrons can exhibit attractive forces under certain conditions, specifically when considering their magnetic dipole moments and specific ...
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Why can multiple eggs support more weight per egg when there are more of them?
With a fracture process the fracturing is usually caused by a local concentration of stress, that is there is some small region where a lot of force is concentrated in a small area and the resulting ...
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If an object suspended by a string is immersed in a liquid, will its weight contribute to the pressure at the bottom of the container?
Assuming the set-up is in equilibrium, and that the atmospheric pressure is zero, the tension in the string would balance the apparent weight of the sphere (the apparent weight being mg-buoyant force)....
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Where does the reaction force go when we slip?
However on a slippery plane when I walk forward, doesn't the plane
also apply a force equal in magnitude and opposite in direction, hence
making me move forward.
Unless the plane is totally ...
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Where does the reaction force go when we slip?
I believe your question is the following:
Your foot exerts a force on the surface and the surface hence responds with a friction reaction force as per Newton's 3rd law. On the slippery surface, your ...
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Where does the reaction force go when we slip?
Force occurs in pairs, i.e action and reaction are simultaneous. When you push the ground, the ground simultaneously exerts a reaction force. This reaction force does not depend on friction.
Now, ...
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Would one be pushing as much as their weight with this machine?
His arms move a longer distance than he is lifted. Therefore the force he needs to push with is lower than his weight. There is a mechanical advantage. Much like to lift the rock in this picture, the ...
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Would one be pushing as much as their weight with this machine?
I was looking at the following machine in the video below, and was
wondering, would one be pushing as much as their weight?
His pushing force is less than his weight due to the mechanical advantage ...
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Why does the work done depend on the frame of reference?
A force perpendicular to velocity doesn't do any work. Work is the change in kinetic energy, so
$$\frac{d}{dt}\left(\frac{1}{2}m \vec{v}\cdot\vec{v}\right) = m\vec{v}\cdot\vec{a} = \vec{v}\cdot\vec{F}...
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Why does force perpendicular to the velocity change only its direction; not the speed?
Most answers rightly point out that a force, in order to achieve what you are stipulating (it changes the direction of the object, not its speed), must be constantly (at each instant) perpendicular. ...
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Why does force perpendicular to the velocity change only its direction; not the speed?
It's really very simple, because both force and Velocity are vectors, not scalars. That is, they have a direction and not just a value. When you exert a force on an object, the resultant acceleration (...
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Why does force perpendicular to the velocity change only its direction; not the speed?
The force perpendicular to velocity does not change the speed of an object because it only affects the direction of motion, not the magnitude of the velocity. This is a consequence of the fundamental ...
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Is the weight of something being dropped the same as the force of something being static?
The answer is very simple. When a body is dropped from a certain height, the quantity of motion is involved. Another name for quantity of motion is linear momentum.
The change in linear momentum is ...
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Forces on spring, Newtons third law
Consider the system which contains the mass, the ideal spring and the Earth (to which the spring is attached in some way).
There are three Newton third law pairs of forces and for each pair the ...
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Forces on spring, Newtons third law
Consider the system which contains the mass, the ideal spring and the Earth (to which the spring is attached in some way).
There are three Newton third law pairs of forces and for each pair the ...
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Forces on spring, Newtons third law
Let $m_s$ be the mass of the spring, $m_b$ the mass of the block and $g$ the gravitational acceleration.
The ceiling is pulled down by a force equal to $(m_s + m_b)g$. It doesn't matter to the ...
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Forces on spring, Newtons third law
There is a force on the block due to gravity and a force on the block due to the spring. These are not newton's third law force pairs, but they do happen to cancel out since the block is moving at a ...
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Why don’t charge carriers constantly accelerate in an electric circuit?
So my question is: how come the charge carriers don’t accelerate
constantly? Is there some kind of balancing force that keeps them at a
constant drift velocity?
The charge carriers alternatively ...
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Is the weight of something being dropped the same as the force of something being static?
A true causation for your demonstration relies in the concept of Impulse. Discarding the conventional answer, if you want to go far beyond and evaluate the truth see https://www.researchgate.net/...
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Plank overhanging off a building — where does the normal force go?
Treat the plank as two parts. Part A, resting on the ground. And part B hanging. The condition for balance will be that part A with its mass (its mass should be calculated proportional to the length) ...
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What happens when my initial applied force is greater than my frictional force?
If you're applying a force against the ground, the faster you go the harder its going to be to apply a force.
For example, if you're on a skateboard and you can swing your leg at 20 mph to push off ...
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What happens when my initial applied force is greater than my frictional force?
Even more profound, if your initial force is exactly the same as your friction force, you'll keep moving if you were already moving.
Of course, nothing beats a practical example. Here is strongman ...
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What happens when my initial applied force is greater than my frictional force?
Friction forces are continuously applied as long as the moving body is in contact with a surface. The friction force is, at least approximately, dependent on the velocity of the body that is moving. ...
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Is the weight of something being dropped the same as the force of something being static?
After falling from height $h$ and impacting elastically with the spring (of constant k) the weight W and top part of spring travel down together by a common deflection $\delta$.
Equating work done to ...
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Does a linearly accelerating spherically symmetric body emit gravitational waves
According to Birkhoff's Theorem, any spherically symmetric body will not emit gravitational waves. <…> But now imagine, we have a spherically symmetric body that is linearly accelerating through ...
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Is the weight of something being dropped the same as the force of something being static?
Weight is the force that the earth does on the block. It doesn't change if it is falling or not.
But the force that the block does on your feet is a different matter. If it is just there in a static ...
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Is the weight of something being dropped the same as the force of something being static?
Your foot brings the falling block rapidly to rest. Suppose the block has been dropped from a height of 0.90 m above the top of your foot. When it reaches the top of your foot it will be falling at 4....
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Is the weight of something being dropped the same as the force of something being static?
When the dropped block hits your foot, it has a certain amount of momentum, p. A force F(t) must be provided over a time interval to bring it to rest, where $\int F(t)$dt = p. The smaller the time ...
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Point forces doing work
This is intended to add one more perspective which is, I believe, consistent with the answers given by @BioPhysicist and @Farcher.
Clearly the energy that raises the boy up the ladder comes from the ...
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Accepted
Newton's third law in thermodynamics
For question 1, when we do a force balance on a body, we include only the forces exerted by other bodies on that body, and not forces which it exerts on other bodies. So the two action-reaction ...
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Newton's third law in thermodynamics
Newton's 3rd law only describes what I consider to be the same force that acts on two objects, not two different forces. And forces not acting on the same object can never sum or cancel each other.
...
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Does a linearly accelerating spherically symmetric body emit gravitational waves
Yes, it would produce waves. Its position and hence its mass distribution relative to a fixed point changes over time, so the quadrupole moment is changing. Since it is accelerating, the second ...
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How to calculate normal force acting on part attached with a screw? Can the force on screws be decreased by lowering the height of the normal force?
For the most general case, of a T-design, I think you are looking at something like this
Where $F$ is the applied force, and $B_x$, $A_y$, and $A_x$ represent the forces provided by the screws to ...
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Why does force perpendicular to the velocity change only its direction; not the speed?
I want to come at this from a slightly different perspective.
If you were writing a computer program to simulate a ball on a string but you wanted to simulate it with forces in Cartesian coordinates, ...
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Why does force perpendicular to the velocity change only its direction; not the speed?
I want to highlight something you said:
Even if we assume that at the given instant , the change caused by the acceleration along it does not contribute significantly and magnitude effectively ...
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Why does force perpendicular to the velocity change only its direction; not the speed?
If we represent the movement in a 2D Cartesian plan, the velocity vector at any instant is $\mathbf v = (v_x,v_y)$. The velocity modulus is $\sqrt{v_x^2 + v_y^2}$. Now suppose that the derivative of ...
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Why does force perpendicular to the velocity change only its direction; not the speed?
The magnitude of a vector $\vec v$ can be expressed as the dot product $v = \sqrt{\vec v\cdot \vec v}$ so its derivative can be expanded as
$$\frac{\mathrm dv}{\mathrm dt} = \frac{\mathrm d}{\mathrm ...
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