Tagged Questions
1
vote
1answer
28 views
Determine the velocity and acceleration of the vertex $B$
1) The bent rod $ABCD$ rotates about the line $AD$ whit a constant angular velocity of $90 rad / s$. Determine the velocity and acceleration of the vertex $B$ when the rod is in the position shown in ...
0
votes
0answers
65 views
Units and use of the formula of the angular acceleration? [closed]
Question: On my document, it is written:
Angular acceleration:
$$ \frac{d\omega}{dt}=r\times \alpha $$
What are the units please?
What are $d \omega$, $dt$ and $r$?
I already know that $\alpha$ is ...
0
votes
2answers
258 views
Vector Nature Of Angular Velocity
I am currently reading about angular position, angular velocity, and angular acceleration. I came across this paragraph that was particularly confusing, and was wondering if someone could perhaps help ...
1
vote
2answers
371 views
Applying angular velocity to a rotation matrix
I have a very simple question. In our project we store an object's orientation as a 3x3 matrix which holds the orthonormal base of that object's local space. For instance if the object is aligned with ...
0
votes
3answers
2k views
Finding Angular Acceleration of rod given radius and angle
A uniform rod is 2.0 m long. The rod is pivoted about a horizontal, frictionless pin through one end. The rod is released from rest at an angle of 30° above the horizontal. What is the angular ...
1
vote
2answers
290 views
motion in the body-fixed frame?
This is really basic, I'm sure: For rigid body motion, Euler's equations refer to $L_i$ and $\omega_i$ as measured in the fixed-body frame. But that frame is just that: fixed in the body. So how ...
2
votes
3answers
1k views
Angular momentum equations
I do not understand this because angular momentum is $L=I\omega$ ($I$ is moment of inertia;$\omega$ is angular velocity) but it I have also seen equations where $L= rmv\sin(x)$. I do not understand ...
-1
votes
1answer
313 views
How to get angular acceleration from spin count and angular velocity [closed]
It would be very good if someone explained me how do you get to the final answer which is already know (3.2 rad/s^2)
Have been given:
ω = 20 = angular velocity (rad/s)
N = 10 full spins
Need to find:
...
1
vote
2answers
500 views
What are the expressions for rotational and translational kinetic energies of a system of point particles?
Consider a system of point particles , where the mass of particle $i$ is $\mu_i$ and its position vector is $r_i$. What are the expressions for translational kinetic energy and rotational kinetic ...
2
votes
1answer
1k views
Merry go round physics problem?
So I have the following statement.
"A merry-go-round is spinning with a fixed angular speed. As a person is walking towards the edge, the force of static friction must increase in order for the ...
1
vote
1answer
160 views
Finding stopping time when only given initial angular velocity and an expression for angular acceleration?
Question:
A wheel starts is spinning at $27\text{ rad/s}$ but is slowing with an angular
acceleration that has a magnitude given by $\alpha(t) = (3.0\;\mathrm{rad/s^4})t^2$. It stops in a time ...
1
vote
2answers
3k views
What is the difference between angular speed and tangential speed in a circular motion?
I was looking a long time for the way the equations of this two speeds are obtained, and i found pretty much nothing important, so can someone explain how are those obtained, and which is the ...
6
votes
3answers
836 views
How is it that angular velocities are vectors, while rotations aren't?
Does anyone have an intuitive explanation of why this is the case?
