Two carts collide, similar to our in-class examples. Cart A has a mass of 2 kg, and is moving to the right at 4 m/s when it bumps into cart B (5 kg), which is moving left at 3 m/s. If the carts stick together after the collision, how fast are they moving?

Answer: 1 m/s to the left

Step-by-step explanation: Considering momentun conservation, this is as follow:

PA+PB = Constant

PA = 2 Kg * 4 m/s to the rigth

PB = 5 Kg * 3 m/s to the left

after collision the two mass go together so the PA+B = Vfinal (mA+mB) = Vfinal (2 kg + 5 kg), the momentum conservation is then

PA-PB=8-15=-7 = Vfinal (7kg)

Vfinal = - 7/7 m/s=-1 m/s