A grocery shopper tosses a 9.0 kg bag of rice into a stationary 18.0 kg grocery cart. The bag hits the cart with a horizontal speed of 5.5m/s toward the front of the cart. what is the final speed of the cart and bag?
Conservation of momentum problem. Look it up in your physics book, but i believe it is:
m1*v1 = m2*v2
9kg*5.5m/s = (9kg+18kg)*v2
Of course this assumes a perfectly elastic collision with NO friction between the cart and ground.