A hinge swings from a horizontal position to a vertical position. So, the hinge moves 90 degrees. In the beginning, the position is horizontal at 0 degrees, and the hinge moves 90 degrees clockwise downwards. The mass of the hinge is 10 kg and the length is 80 cm. Friction and air resistance are not taken into account.

1. Calculate the angular acceleration of the hinge at the start, in a horizontal position. Give the answer with the unit.

2. Calculate the angular velocity of the hinge in the vertical position. Give the answer with the unit.