Answer the question below. Use the rubric in the materials for help if needed. Two train cars with the same mass (30,000 kg) are traveling in the same direction when they collide. Train Car A has a velocity of 10 m/s and Train Car B has a velocity of 5 m/s. What is their total momentum after the collision? Make sure to show all your work and include proper units.

Two identical stars with mass m orbit around their center of mass. each orbit is circular and has radius r, so that the two stars are always on opposite sides of the circle. (a) find the gravitational force of one star on the other. (b) find the orbital speed of each star and the period of the orbit. (c) how much energy would be required to separate the two stars to infinity?