A 0.504 kg metal cylinder is placed inside the top of a plastic tube, the lower end of which is sealed off by an adjustable plunger and comes to rest some distance above the plunger. The plastic tube has an inner radius of 7.07 mm, and is frictionless. Neither the plunger nor the metal cylinder allows any air to flow around them. If the plunger is abruptly pushed upwards, increasing the pressure among the plunger and the metal cylinder by a factor of 1.35, what is the initial acceleration of the metal cylinder? Suppose the pressure outside of the tube is 1.00 atm.