Question

A rotor shaft has unbalances as shown in the figure. The total dynamic reaction at the support is

• A. $me{\omega }^2$
• B. $me{\omega }^2\frac{a}{l}$
• C. $me{\omega }^2\frac{l}{a}$
• D. none

Answer 1

The correct option is D none

$\text{Dynamic reaction at}A=Me{\omega }^2\frac{a}{l}$

$=R_A\text{(Downwards)}$

$\text{At}B=me{\omega }^2\frac{a}{l}\text{(upwards)}=R_B$

$\text{Total dynamic reaction}=R_A+R_B$

$=-me{\omega }^2\frac{a}{l}+me{\omega }^2\frac{a}{l}=0$