A 0.015 kg marble sliding to the right at 22.5 m / s on a frictionless surface causes an elastic frontal collision with a 0.018 kg marble moving to the left at 18 m / s. After the collision, the first marble moves to the left at 18 m / s. Find the speed of the second marble after the collision.

While strolling downtown on a saturday afternoon, you stumble across an old car show. as you are walking along an alley toward a main street, you glimpse a particularly stylish alpha romeo pass by. tall buildings on either side of the alley obscure your view, so you see the car only as it passes between the buildings. thinking back to your physics class, you realize that you can calculate the car's acceleration. you estimate the width of the alleyway between the two buildings to be 6 m. the car was in view for 0.6 s. you also heard the engine rev when the car started from a red light, so you know the alpha romeo started from rest 4 s before you first saw it. find the magnitude of its acceleration.