All Questions
31 questions
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How to calculate angular and linear components of a force acting upon a 3d object?
apologies if this isn't worded great: I don't know all the technical terms for what I'm describing.
Given a 3D object in space (no gravity or air resistance or anything), let's say its center of mass ...
0
votes
1
answer
75
views
Does spinning the umbrella slow down the fall more?
Ignoring its structural weakness, if you jump from some height and use an umbrella to slow down the fall, would making it spin while you're falling affect the speed in any way?
- 379
0
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0
answers
22
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Closed form solution for the linear acceleration of a particle on 3D rotating object given momentum and MoI?
Is there a closed-form solution for the linear acceleration of a particle on a rigid body undergoing some arbitrary rotation in 3D with no external forces, given its angular momentum vector and its ...
- 357
0
votes
1
answer
129
views
Absolute Angular Velocity - How to use?
From my dynamics course, we were introduced to the so-called absolute angular velocity of a rigid body. Below is a short diagram:
The following equation for the velocity of point P on a rigid body is ...
- 31
0
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1
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78
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To find the displacement of a rolling body
When calculating the displacement of a rolling body do we just calculate the displacement due to Vcom in a particular time t or additionally need to consider also the displacement that may be produced ...
1
vote
1
answer
58
views
Estimating angular velocity of rigid body via position
Suppose you have current state of a rigid body is $S_t = [\theta_t, \phi_t, \psi_t]$ and your past state is $S_{t-1} = [\theta_{t-1}, \phi_{t-1}, \psi_{t-1}]$
How would you estimate angular velocity ...
- 982
1
vote
1
answer
54
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Vehicular Dynamics [closed]
Consider an open differential connected to two wheels on each side. The wheels are flat discs and are 1400 mm apart. This car is making a turn of radius 7 m at a constant angular velocity of 30 ...
- 11
0
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0
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61
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How is the angle of the front wheel found in Bicycle Kinematics Model for a Car
My question is, in a 4 wheel model, the front wheels have different angles. To simplify things bicycle model is used. In the bicycle model, there is an imaginary wheel in the middle of the front ...
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1
answer
156
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Frictional wheels without slipping (gear system)
In the figure below it is stated that the friction force should always be greater than the tangential force in order to prevent slipping between two frictional wheels. My question is that if we apply ...
- 113
0
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1
answer
148
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Analytically proving that the yo-yo rolls to the right (angular kinematics) [closed]
Assume that the yoyo is always rolling without slipping.
Physical experiments shows that the yoyo would roll to the right.
I'm aware of some ways to show this without analytically solving the system (...
- 131
0
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0
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65
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"Kinematic" dynamics or dynamics that ape kinematic movement
This is a question related to unity's physx engine, but also a general question as well.
How do you make linear and rotational dynamics work kinematicaly? For example, I add a force to an object and ...
- 75
2
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3
answers
195
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In Uniform Circular Motion, why does the normal accelaration not change the magnitude of velocity?
According to pythagorean theorem V2 should be greater then V1.But why doesn't it happen?
- 315
1
vote
2
answers
2k
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The direction of the centripetal force in a vertical circular motion under uniform gravity
Consider the vertical circular motion of a point mass connected to the centre by rigid string. Here the uniform gravity $m\vec{g}$ acts.
I illustrated the situation in the diagram below.
Here if we ...
- 485
5
votes
1
answer
1k
views
Relationship between Radius of curvature and Instantaneous Axis of Rotation
Consider a Ring (radius $r$) rolling without slipping with angular speed $\omega$ on the surface. We want to find the radius of curvature of the top most point.
1.The radius of curvature(R): ...
- 1,325
9
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7
answers
4k
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Two rotating discs with same angular momentum when brought in contact completely stop. Why is the angular momentum not conserved in this case?
Two discs mounted on different thin, lightweight rods oriented through their centres are made to rotate about their axes seperately such that the angular momentum of the two about their respective ...
- 91
0
votes
2
answers
314
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Why is $\theta=\beta/2?$ - Kinematics [closed]
An aircraft is flying horizontally in a circle of radius $b$ with
constant speed $u$ at an altitude $h$. A radar tracking unit is
located at $C$. Write expressions for the components of the ...
- 209
0
votes
0
answers
116
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Angular velocity of rigidly rotating orbit in 3D
Consider a circle in 3-dimensional space. On this circular orbit, a rigid bead moves, thus changing its angle $\phi$ with a reference radius on the circle.
The intrinsic angular velocity is given by ...
- 1,813
0
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2
answers
80
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Can someone explain to me about Kinematics relation? [closed]
This is my first time asking in stackexchange and I'm just an ordinary Indonesian highschooler so I'm sorry if I do anything wrong.
I can't describe the question with words so I attached a picture of ...
0
votes
0
answers
70
views
Determine Linear and Angular acceleration of a ball in 3D space
I am trying to simulate this situation.
Suppose that I have a Ball (sphere) in Vacuum with no forces acting on it. Now If I apply a force at a point on the surface of the ball, the force can be ...
- 11
0
votes
1
answer
305
views
How would you calculate the speed of a rotating disk with an object that enters and leaves the disk? [closed]
How would I find the speed of a moving object that enters a rotating circle and then leaves it again?
The object moves at s and the distance between entering and leaving is calculable. The object ...
- 101
0
votes
2
answers
2k
views
Angular acceleration and angular velocity relationship
It is given that angular velocity is the rate of change in the angular position of a body while the angular acceleration is the rate of change in angular velocity.
Other relationships include that ...
- 99
0
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2
answers
381
views
Kinetic energy in translation and rotation based on frame of reference
How does translational kinetic energy of a system depend on frame of reference where as rotational kinetic energy does not depend on reference frame?
2
votes
1
answer
979
views
Relationship between centripetal and angular acceleration?
Regarding circular motion...
The way that I know of how to derive the centripetal acceleration is based on the geometrical representation of two instantaneous linear velocities of equal magnitudes on ...
- 21
0
votes
1
answer
3k
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What is the purpose of torque in projectile motion?
Torque, $\tau$ is defined as:
$$\vec{{\tau}} = \vec{r}\times\vec{F}$$
Intuitively, it's the rotational effect of force. However, using the above definition of torque we can calculate the torque ...
- 375
0
votes
3
answers
1k
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Is angular momentum conserved if centripetal force is increased?
Let a mass $m$ be attached to the end of a light rigid rod of length $r$. The other end of the rod has a loop of non stretchable thread attached.
I put my finger into the thread loop and rotate the ...
- 45
6
votes
3
answers
473
views
A dumbbell rolls down a slope, what happens when it touches the ground?
As in the title, our Physics teacher gave us this brain teaser after learning introductory motion. "If I have a dumbbell [with bigger weights than handle] that is rolling down an incline with only ...
- 2,366
1
vote
3
answers
3k
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Why the similarity in the Equations of Motion for Rotational and Rectilinear Motion?
These are the equations of motion given constant acceleration, for first rectilinear and then rotational motion.
Rectilinear Motion:
Rotational Motion:
While the variables have changed, and the ...
- 293
0
votes
1
answer
987
views
Force required to rotate a rod around an axis [closed]
The problem I'm trying to solve is:
How much force, momentarily applied to the rod, is required to rotate it around an axis by a given degree? Assuming there is friction applied at the axis (...
- 123
5
votes
2
answers
2k
views
Rolling as pure rotation
In my book the following statement was written and I didn't understand it well. Can anyone explain it in a more simple way?
Figure 11-6 suggests another way to look at the rolling motion of a ...
- 1,426
7
votes
1
answer
3k
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Does a tire need to slip to generate force?
Recently, I have been doing some research on racing and tire modelling. While I was doing this, I encountered many curves like those shown below.
(source: insideracingtechnology.com)
While I ...
- 427
2
votes
1
answer
2k
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Non-commutative property of rotation
Addition of angles are non-commutative in three dimensions. Hence some other angular vector quantities like angular velocity, momentum become non-commutative. What is the physical significance of this ...
- 1,985