A bullet is fired through a wooden board with a thickness of 11.0 cm. The bullet hits the board perpendicular to it, and with a velocity of 410 m/s. The bullet then emerges on the other side of the board with a velocity of 246 m/s. Assuming constant acceleration (rather, deceleration!) of the bullet while inside the wooden board, calculate the acceleration. (Note that the positive velocities define the positive direction to be in the bullet's direction of travel. If the acceleration is in the same direction as the velocity, the acceleration is positive. If the acceleration is in the opposite direction from the bullet's velocity, the acceleration is negative.)