7. A \( 0.2-\mathrm{kg} \) particle P is constrained to move along the vertical-plane circular slot of radius \( \mathrm{r}=0.5 \mathrm{~m} \) and is con-fi ned to the slot of arm OA, which rotates about a horizontal axis through O with a constant angular rate \( \Omega=3 \mathrm{rad} / \mathrm{s} \). For the instant when \( \beta=20^{\circ} \), determine the force N exerted on the particle by the circular constraint and the force \( R \) exerted on it by the slotted arm.