Ok, did I do this correctly?(adsbygoogle = window.adsbygoogle || []).push({});

The question goes:

Determine the angular velocity and angular acceleration of the disk and the link AB at the instant A rotates through 90 degrees.

See attachment for the figure.

What I did--first the disk:

Assuming [itex]\alpha_{disk}[/itex] is constant

[tex]

\alpha_{disk}=\alpha_0=\alpha_{90}=6\frac{rad}{s^2}

[/tex]

[tex]

\omega_{90}^2=\omega_{0}^2+2\alpha(\theta_{90}-\theta_{0})

[/tex]

[tex]

\omega_{90}=\sqrt{(5\frac{rad}{s})^2+2(6\frac{rad}{s^2})(\frac{\pi}{2})}=6.622\frac{rad}{s}[/tex]

So, angular velocity of the disk is 6.622 rad/s, and angular acceleration of the disk is 5 rad/s^2.

Now for the link:

[tex]

\vec{v}_A=\vec{ \omega }\times \vec{r}_A

[/tex]

[tex]

\vec{v}_A=\omega(r_A)i=6.622\frac{rad}{s}(0.5\frac{ft}{rad})=3.311\frac{ft}{s}i

[/tex]

[tex]

\vec{v}_B=\vec{v}_A+\vec{ \omega }\times \vec{r}_{B/A}

[/tex]

Used trig to find this:

[tex]

\vec{r}_{B/A}=2\cos 19i+2\sin 19j

[/tex]

[tex]\vec{v}_B=3.311i+\omega(0.652i-1.891j)[/tex]

[tex]

v_bi=3.311i+0.652\omega i

[/tex]

[tex]

v_bj=-1.891\omega j

[/tex]

solve simultaneously and I get:

[tex]

\omega=-1.302\frac{rad}{s}

[/tex]

Is this right thus far?

[edit]forgot picture

**Physics Forums | Science Articles, Homework Help, Discussion**

Dismiss Notice

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Homework Help: Angular velocity and acceleration of a flywheel system

**Physics Forums | Science Articles, Homework Help, Discussion**