The picture above shows a U-shaped tube with two disks floating on top of water. The tube is cylindrical, and the right arm has twice the radius of the left arm. The caps have negligible mass, are watertight, and can freely slide up and down the tube. A mass of 1 kg is placed on each disk leading to a height difference between the two sides, as shown. How much mass do you have to add to make the difference in height zero at equilibrium and where should you add it? Group of answer choices Add 1kg to the right side Add 1kg to the left side Add 2kg to the right side Add 2kg to the left side Add 3kg to the right side Add 3kg to the left side Add 4kg to the right side Add 4kg to the left side Not possible to make the height difference 0