Suppose you are holding an air-filled ball of mass m = 0.3 kg into the water at a certain depth. When you release it, it will be accelerated upward. Three forces act on the ball after it is released: an upward buoyant force B =+574 N, the ball's weight W = mg, and a resistance force R = -280 N. What is the acceleration a (magnitude and direction) of the ball? (Note: boldface letters indicate vectors.)