A 0.50kg cart moves to the right at 2.0m/s on a frictionless track and collides with a 0.30kg cart moving to the left at 1.0m/s. Immediately after the collision the carts stick together. What is their common velocity just after the collision?
a) 1.6m/s to the right
b) 0.44m/s to the right
c) 0.88m/s to the right
d) 0.88m/s to the left