A mass driver consists of a conducting bar of mass m and length I resting over two metal rails that are connected to a battery. As a current I is pumped through this circuit the induced magnetic field B accelerates the conducting bar along the rails until it launches off the end. E BI A lunar colony uses a mass driver to accelerate cargo into space where orbiting spacecrafts pick up them up. For this problem ignore friction, air resistance (reasonable on the moon), and the force of gravity (not so reasonable but we will do it anyway). The length of the bar that holds the cargo is = 10 [m], the magnetic field strength is B = 1 [T], and the current in the circuit is = 102 [A]. a) The lunar escape speed is 2.3 [km/s]. How long does the rail need to be to launch a 1 [ton] payload into orbit? Express your answer in [km]. b) Is this shorter or longer than the distance between Honolulu and San Francisco?