Questions tagged [forces]
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 the [particle-physics] tag for decay channels due to forces and [newtonian-mechanics] or one of the other subtopics of [classical-mechanics] for the dynamics of classical systems.
9,421 questions
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Science Olympiad Machines question [closed]
My son is practicing with his high school Science Olympiad team and came across this question: His source includes an answer, without explanation, that the coefficient of friction is $\mu\approx3.3$. ...
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3 votes
3 answers
281 views
Longitudinal waves in a tin can telephone
What kind of wave travels true the string of a tin can telephone? Most places say that its a longitudinal wave, if that's the case then why when the string is tensioned the message gets louder?
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Does a stationary electron hit by an electromagnetic wave move diagonally?
If a stationary classical electron is hit by an electromagnetic wave, does it move diagonally, since the electric field moves the electron and the magnetic field of the EM wave causes a Lorentz force ...
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-1 votes
3 answers
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What force(s) is rotation made of? [duplicate]
Can the rotation of an object be viewed as the result of two perpendicular forces ('push' and 'pull') that have combined? When I spin a wheel there is a 'push force' at a right angle to the wheel's ...
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I need help on a conceputal problem for kinetic friction problem [closed]
If the coefficient of friction were to increase, how would this affect the total travel time? Explain why by referring to both intervals of motion. Use at least one physics representation as part of ...
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Finding correct tension in simple pendulum [closed]
Please forgive me if I am being too much stupid. But please can anybody tell me why I am getting two different values of the Tension for the same pendulum. Its not at equilibrium. As it oscillate due ...
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1 answer
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Confused about the Kinetic Energies of a many-body system
My Question stems from the following problem: Consider two resting Point Masses, each with mass $m$, which are connected (the connection having no mass). A Force $F$, which is always perpendicular to ...
5 votes
2 answers
617 views
Is not pulling a massless spring after hanging it equivalent to pulling it from both sides?
Let us hang a massless spring and pulled it downwards with force $F$. (You may neglect gravitational force or include it within $F$.) Let due to this the spring extended by $x$. Now let me pull the ...
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2 answers
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How could one show that kinetic friction is a non-conservative force?
The question is not to talk about why kinetic friction is non-conservative, but rather if there is a way that I could show mathematically that the work done by kinetic friction is path-dependent?
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1 vote
2 answers
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Can a Massless Pulley with no friction be treated as a massless circular object with no friction?
A pulley usually involves a rotating axle to change the direction of tension. However I read in my Textbook that for an ideal pulley, this need not be the case, and you do not need to consider any ...
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0 votes
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Accounting for magnetic forces in Lagrangian mechanics [duplicate]
For conservative forces the Euler-Lagrange equation is used to find the relevant details about the system. However magnetic forces are not conservative do not perform any work on an moving charged ...
-1 votes
1 answer
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What pressure is used in Bernoulli's equation in fluid-dynamics?
Hereinafter, the term “fluid” will be used to mean “ideal fluid” (i.e., an incompressible fluid without friction). The fluid flows to the right through a horizontal pipe at a speed $v$. Then Bernoulli'...
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2 votes
2 answers
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Will a frictionless rope in space retain its shape if all segments move tangentially with equal velocity?
Suppose we have a uniform, massive, flexible, frictionless and non-stretchable rope in space, initially shaped arbitrarily. Each infinitesimal segment of the rope is given the same velocity in the ...
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0 votes
2 answers
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Confusion in finding stress in accelerated body
On the left side, my teacher shows the method for finding stress on a small element dx of a rod. He treats the tension as the restoring force. However, my question concerns the diagram on the right ...
1 vote
3 answers
107 views
Newton's 2nd Law [duplicate]
We know: $$ F = \frac{dp}{dt} $$ and: $$p = mv$$ so by simple calculus, is it correct to write: $$ F = m \frac{dv}{dt} + v \frac{dm}{dt} $$ If not, why not?
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