A block of mass 0.50 kg is moving with a speed of $2.00 \mathrm{~m/s}$ on a smooth surface. It strikes another mass of 1.00 kg and then they move together as a single body. The energy loss during the collision is
(1) 0.16 J
(2) 1.00 J
(3) 0.67 J
(4) 0.34 J