Arailroad car of mass 2.30e+4 kg moving with a speed of 3.00 m/s collides and couples with two other coupled railroad cars each of the same mass that are already moving in the same direction at a speed of 1.10 m/s. what is the speed (in m/s) of the three coupled cars after the collision?

Consider a uniformly charged ring in the xy plane, centered at the origin. the ring has radius a and positive charge qdistributed evenly along its circumference. a)what is the direction of the electric field at any point on the z axis? . b)what is the magnitude of the electric field along the positive z axis? use k in your answer, where k=14πϵ0. d)the ball will oscillate along the z axis between z=d and z=−d in simple harmonic motion. what will be the angular frequency ω of these oscillations? use the approximation d≪a to simplify your calculation; that is, assume that d2+a2≈a2. express your answer in terms of given charges, dimensions, and constants