Problem $1$: The slender $10-$kg bar AB is horizontal and at rest. The spring has an unstretched

length of $1\mathrm{.}5$ m and a spring constant of $15$ kN$/$m$.$ When the bar rotates

clockwise $45$o after it is released, determine:

$($a$)$ The angular velocity of the bar, $?$

$($b$)$ The angular acceleration of the bar, $?$

$($b$)$ The reaction force at A: $$ and $?$

Solution: