21. The maximum acceleration of a car while towing a second identical car, compared to its acceleration with no car in tow, is A. one half. B. one third. C. one fourth. D. the same. E. none of these 22. If an alien life form would suddenly cause the Sun to collapse into a black hole, the Earth . would get sucked in immediately B. would fly off in a straight line C. would fly off in a hyperbolic path D. would spiral in rather quickly on cosmic time scales E. something else