Physics collisions question?

A battleship that is 6.00 ✕ 107 kg and is originally at rest fires a 1400–kg artillery shell horizontally with a velocity of 675 m/s.
(a)
If the shell is fired straight aft (toward the rear of the ship), there will be negligible friction opposing the ship's recoil. Calculate its recoil velocity in meters per second.
m/s
(b)
Calculate the increase in internal kinetic energy in joules (that is, for the ship and the shell). This energy is less than the energy released by the gun powder — significant heat transfer occurs.
J

billrussell422019-01-14T23:07:34Z

6.00 ✕ 107 kg ?? what does this mean?