A cylinder which is in a horizontal position contains an unknown noble gas at 54700 Pa 54700 Pa and is sealed with a massless piston. The piston is slowly, isobarically moved inward 0.150 m 0.150 m , while 16800 J 16800 J of heat is removed from the gas. If the piston has a radius of 0.272 m 0.272 m , calculate the change in internal energy Δ U ΔU of the system.