Two balls are hung from cords. The first ball, of mass 1.0 kg, is pulled to the side and...

Two balls are hung from cords. The first ball, of mass 1.0 kg, is pulled to the side and released, reaching a speed of 2.0 m/s at the bottom of its arc. Then, as shown in Figure Q9.20, it hits and sticks to another ball. The speed of the pair just after the collision is 1.2 m/s. What is the mass of the second ball?

A. 0.67 kg

B. 2.0 kg

C. 1.7 kg

D. 1.0 kg