A tag for questions about rotational motion, including angular velocity and angular acceleration.
Questions tagged [rotational-kinematics]
1303 questions
10
votes
4 answers
If angular velocity & angular acceleration are vectors, why not angular displacement?
Are angular quantities vector?
... It is not easy to get used to representing angular quantities as vectors. We instinctively expect that something should be moving along the direction of a vector. That is not the case here. Instead,…
user36790
3
votes
1 answer
Definition of angular velocity
I'm trying to follow the Feynman lectures and I'm stuck on a particular piece. Let me frame it for you before I ask my question. Nobody does it better than the author himself,
we must find out how a particular particle moves when the angular…
sciencenewbie
- 321
2
votes
4 answers
How can the linear velocity under rotational motion be along the tangent?
Under rotational motion, an object moves along the circumference of the circle, so, it's linear velocity should be the linear displacement between two points over a period of time.So,the linear velocity should be along a secant of the circle, with…
Rayhan
- 167
2
votes
2 answers
Why is the magnitude of friction acting on the rear wheels greater than the magnitude of friction acting on the front wheels?
When a car is accelerating on a horizontal road , friction acts in the forward direction on the rear wheel and in the backward direction on the front wheel .
But I am not able to understand why the friction acting on the rear wheel is greater in…
2
votes
2 answers
Intrinsic Concurrent Pitch/Yaw/Roll Rotation Between Two Rotation Matrices
Given an object with a rotation matrix, how do you calculate the pitch, yaw, and roll velocities that needs to be applied over time for the object to reach a goal rotation matrix given that:
The x-Axis is left, the y-Axis is up, and the z-axis is…
Tyler
- 23
- 2
2
votes
0 answers
Translational acceleration due to rotation
Sorry for boring you, my friends. I am haunted by re-deducing an expression of translational acceleration in ANSYS theory reference about acceleration effect. It takes the form of:
$$\lbrace a_t^r \rbrace = \lbrace \omega \rbrace \times \left(…
Zihan Shen
- 81
2
votes
1 answer
Minimum velocity of the particle at the highest point
A particle of mass m is fixed to one end of a light rod of length l and rotated in a vertical circular path about its other end. What is the minimum speed of the particle at the highest point?
It occurs to me that the answer should be zero. But I…
curiousbrain
- 213
2
votes
3 answers
Rotation of center in rotational motion
For a wheel in pure rotational motion;
Does the center rotate?
Is there a point in wheel which do not rotate?
What can we say about angular velocity of the center?
From where we can start to use the term "center" for that area?
Thanks.
2
votes
2 answers
Non-constant angular velocity
In this paper about Backstepping controll of a quadrotor helicopter an algorithm for control is described, but I have hit a dead end.
In equation 15 it is described the part of state space for the angular and translation motion of a rigid body.
The…
Paulo Neves
- 131
1
vote
2 answers
Relative linear velocity of a particle to a rotating object
I am trying to calculate the "relative linear velocity" of a particle moving over a rotating object.
According to this paper (section 2.2) I am reading the relative linear velocity is calculated by:
$$
v'= v - \omega r
$$
Where $v$ is the velocity…
Lerp
- 153
1
vote
1 answer
How the rotation is possible applied onto derivatives?
After reading kinematics of mobile robot or the rigid-body, I get something not quite undersand why it it possible.
Suppose that coordinate system $A$ is the global or the reference frame, in which a robot with a rigid-body frame or local coordinate…
arifle
- 13
1
vote
2 answers
Will a rotating body show translational motion in space?
Suppose I rotate a fidget spinner and let go of it in space. It will have some angular momentum. My question is will it move forward because of that angular momentum?
I mounted a fidget spinner on a board using some toothpicks and after spinning…
Pranav K
- 540
1
vote
1 answer
Is it easier to balance a free-standing ladder when standing on the bottom step or the top step?
This video shows someone climbing a ladder not resting against a wall: https://youtu.be/bWOSbEtDAas . I was wondering if it's harder to balance the ladder when you're standing near the bottom, or standing near the top.
Intuition for why it might be…
Craig Gidney
- 6,164
1
vote
2 answers
How can I determine the rotation point and the rotation axis if I know two velocities of a rigid body?
In case of a "2D" rigid body I can find a vector $\vec{r}_1$ that is perpendicular to the
velocity $\vec{v}_1$ at point $p_1$,
$\vec{r}_1\perp \vec{v}_1$ at point $p_1$,
and the same for point $p_2$,
$\vec{r}_2\perp \vec{v}_2$ at point $p_2$.
The…
Eli
- 11,878
1
vote
1 answer
Falling spool acceleration explanation
In this example both spools A and B have the same downward acceleration. Why would the net downward force on Spool A be the same as for Spool B despite having more total kinetic energy?
lleontan
- 11