All Questions
Tagged with inertia classical-mechanics
35 questions
2
votes
2
answers
773
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Using the principle of inertia to motivate the principle of least action?
Can we motivate the principle of least action with the principle of inertia that causes a mass particle to resist changes in its momentum? After all, the principle of inertia is the starting point and ...
- 733
1
vote
1
answer
75
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How density of fluids is would affect inertia?
I was watching that movie Event Horizon and they use water as an instrument to protect passengers of a space vessel from 30G acceleration, so my question is about a similar scenario, what would happen ...
- 11
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votes
4
answers
254
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How can you figure out when inertia or momentum is keeping the object in motion?
If we consider the case of Earth, inertia carries the Earth forward (inertia alone will make the Earth go out of orbit so gravity keeps it in orbit around the sun), but if we consider the case of a ...
- 419
0
votes
7
answers
954
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Why does "net force" being zero not mean that the parachuter becomes stationary in the atmosphere?
Take the typical phyiscs / classical mechanics example of a parachuter descending at constant speed. The two forces acting on the parachuter are weight, which has direction towards the ground, and air ...
- 929
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votes
1
answer
48
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Decrease of the rotation speed of a wheel with inertia, when we stop applying rotational force to it [closed]
Let's say we have a wheel rotating at a constant speed $s$.
Suddenly at time $t=1$ we stop applying force to it.
What is the law for the decrease of the speed, until it stops?
I guess it will look ...
- 183
1
vote
2
answers
50
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An object on top of a rotating mass like earth
Why do objects fall down in same place on the rotating earth? I get that newton's first law is the reason an object falling on a high speed train will maintain the same velocity as a train and ...
- 71
0
votes
3
answers
95
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Moment of inertia of a solid sphere; spot the mistake [closed]
What an I doing wrong?:
$I = \int r^2dm$
$M = \rho \frac{4}{3} \pi r³$
$dM = \rho \frac{4}{3} \pi 3r²dr = \rho 4 \pi r²dr$
$I = \rho 4π \int r^4dr = \rho 4π \frac{r^5}{5} = \frac{3Mr^2}{5} = \frac{3}{...
- 78
1
vote
1
answer
749
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Integral Issue for Inertia of Disk
I am currently following Taylor's "Classical Mechanics" and I am trying to understand creating the correct integrals to solve some problems related to the inertia of various shapes. I am to ...
- 27
0
votes
2
answers
344
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Physics of pushing the top of a box a little bit to make it rock back and forth
Context:
I'm trying to make a simulation of a box that you can apply force to the top and it will oscillate back and forth until the energy in the system reaches equilibrium again.
Visual ...
- 111
1
vote
0
answers
47
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Equivalence among three kinds of mass
If there are three kinds of mass
(1) resistance (classical inertial mass, rest mass)
(2) sensitivity to gravity (weight)
(3) creation of gravity,
the Eotvos experiment shows the proportionality ...
user281839
20
votes
6
answers
8k
views
Flying a drone in a moving car/airplane
Why does a drone fly with respect to the air in a moving car/airplane, but not in an elevator as shown in this clip: What Happens If You Fly a Drone In An Elevator?
I understand that the drone will ...
- 415
0
votes
1
answer
788
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Does the Higgs field explain inertia?
As far as I understand it the Higgs field leads to the creation of rest mass for certain elementary particles but does it explain the phenomenon of resistance to acceleration associated with rest mass?...
- 5,991
11
votes
4
answers
1k
views
Does general relativity explain inertia?
As far as I understand it general relativity does not explain the origin of the inertial mass $m_i$ in Newton's law of motion $\vec{F}=m_i\ d\vec{v}/dt$ but rather it simply applies the concept to ...
- 5,991
0
votes
1
answer
113
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Working principle of an accelerometer
I'm trying to confirm my concepts regarding inertia and accelerometers. Need to verify / correct my thoughts, which are as follows:
Inertia is the property of matter to resist a change in its state ...
- 1,278
0
votes
1
answer
33
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An expanding, sliding charged tube's self-imposed electromagnetic induction
If I have a simple cylindrical electrically-insulating tube possessing a net electrostatic charge and allow the tube to slide parallel to the tube's axis, that tube will possess electric currents ...
- 129
1
vote
1
answer
94
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Why does things travel in a straight line in inertial frames?
Why does physical entities travel in straight paths in a flat space-time and in geodesic in curved spacetime? Is it due to Inertia? If it is, then why does waves also follow the same pattern?
1
vote
3
answers
200
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Where exactly is inertia stored? [closed]
Suppose you have the power to take a snapshot of an object containing all its information. Say a ball was thrown to a direction to your right and you took a snapshot of it. This snapshot contains all ...
- 231
0
votes
0
answers
115
views
Calculating inertia of motor
I'm currently working on a project, and for futher calculations down the road (the controller of the mechanical system) I need to calculate, as accurately as possible the interia of the system.
I'm ...
- 121
0
votes
1
answer
106
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Centrifuge Artificial Gravity?
I just saw the following video: NASA centrifuge. In video, a person is walking on a huge spinning centrifuge.
But his weight is still acting downwards and there is no supporting force which will keep ...
- 251
6
votes
2
answers
5k
views
How to find the axis with minimum moment of inertia?
If a system of particles is given, in a 2D plane, with particles having masses $M_1$, $M_2$, $M_3, \ldots M_n$ and coordinates $(x_1,y_1)$, $(x_2,y_2)$, $(x_3,y_3), \ldots (x_n y_n)$,
then how can one ...
-1
votes
2
answers
842
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Inertial force in a bus [duplicate]
While i am standing in a bus that is accelerating an inertial force is acting on me in the direction opposite of acceleration (I understand that). But, what is the magnitude of that force.I thought it ...
- 161
0
votes
1
answer
847
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What causes inertia? [duplicate]
Inertia forms the basis of Newtonian physics,but nothing really explains it.I know that it is generally accepted in classical physics,but can it's origin be explained?Maybe be relativity or quantum ...
- 454
2
votes
1
answer
90
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How should one determine the motion of extremely large extended objects?
[To put this question in context, I was reading "How much time will it take to move an object whose length is equal to one light year?" and don't really feel satisfied by the answer that has been ...
- 4,916
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2
answers
6k
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Split moments of inertia into vectors - Right thing to do?
Let's say that we have the moment of intertia:
$$J = mR^2$$
And the mass $m$ is on the $(x, y)$ position. Can I say that moment of intertia is then:
$$J = mR^2 = m\sqrt{x^2 + y^2} ^2 = m(x^2 + y^2)$...
- 161
1
vote
2
answers
884
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Ball inside an accelerating frame
Why does a ball inside a moving bus at rest start moving backwards when the bus suddenly accelerates? Also does the moving ball have some acceleration?
This is my theory:
Initially the bus and the ...
- 19
1
vote
0
answers
937
views
calculation of moment of inertia referred to motor shaft?
Is this equation valid for a given mechanical system
The Inertia of the motor is $J_m$,there is no loss in the system.then conservation of energy can be used.
the motor is revolving with speed $\...
- 123
0
votes
1
answer
511
views
Mass, Weight and Inertia
In The Feynman Lectures on Physics Vol-1, it is written
How hard it is to get a body going is one thing, and how much it weighs is something else. Weight and inertia are proportional, and on earth'...
0
votes
2
answers
203
views
Is this the correct way to think about why static friction is directed radially during a turn on a level surface?
So after much pondering of the fact that the net static friction force points in the center, perpendicular the tangential motion, I thought of this explanation.
If we look at a car travelling around ...
- 1,187
4
votes
3
answers
2k
views
Physical meaning of the moment of inertia about an axis
In the context of rigid bodies, the inertia tensor is defined as the linear map that takes angular velocity to angular momentum, that is, the linear map $I : \mathbb{R}^3\to \mathbb{R}^3$ such that
$$...
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2
votes
4
answers
6k
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Which factors can help a car flip on a turn?
I am not sure if this is the right place to ask it, but this is a question that I thought today, and it gave me some curiosity to understand. Imagine that a car will curve, we can say the turn is a ...
- 365
0
votes
1
answer
385
views
Does stretching a spring with a relatively high spring constant value require more force because of its inertia?
Other than the fact that a spring has a relatively high spring constant (say 1000 N/m) and therefore requires more force per meter to stretch (not bend or twist).
5
votes
7
answers
10k
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Can we explain Newton's first law mathematically?
At constant speed there is no acceleration. $(f'(x)=v'=0=a)$ .If $a=0$ then $F=ma=0$ and therefore no force acts on the object so the object will continue in the same direction, if any. This is only ...
- 1,053
-1
votes
1
answer
729
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Doubt in law of mutual interaction
Book: Classical mechanics (textbook) by Douglas Gregory (cambridge publications)
Law of mutual interaction states that when two particle (let it be P1 and P2) interacts, the particle (P1) induces an ...
1
vote
0
answers
186
views
Closed-form equation for orientation and angular velocity over time
If a rigid body, rotating freely in 3d, experiences no friction or other external forces and has an initially diagonal inertia matrix $\mathbf{I}_0$ (with $I_{11}>I_{22}>I_{33}>0$) and ...
- 375
2
votes
1
answer
1k
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Instability of a thrown tennis racquet [duplicate]
Someone once mentioned to me that it's impossible to throw a tennis racquet (or similarly shaped object) into the air, perpendicularly to the string plane, in such a way that it won't turn.
What is ...
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