An insulated 2-m3 tank is to be charged with r134a from a line flowing the refrigerant at 3 mpa, 90◦c. the tank is initially evacuated, and the valve is closed when the pressure inside the tank reaches 3 mpa. find the mass in the tank and its final temperature

Point charges q1=+2.00μc and q2=−2.00μc are placed at adjacent corners of a square for which the length of each side is 1.50 cm . point a is at the center of the square, and point b is at the empty corner closest to q2. take the electric potential to be zero at a distance far from both charges. part a what is the electric potential at point a due to q1 and q2? express your answer with the appropriate units.