3. (5 points) A train engine pulls two identical cars behind it. Car 1 is attached directly to the engine, and car 2 is attached to car 1. The engine and cars are speeding up. The force of car 1 on car 2 is the force of the engine on car 1. a. Greater than b. Less than C. Equal to d. There is no force on either car 4. (5 points) Raindrops fall at different speeds; some fall quite quickly, others quite slowly. Why might this be true? a. The different raindrops have different drag coefficients. b. The different raindrops have different masses c. The different raindrops have different cross sectional areas d. The different raindrops fall through air of different densities. 5. (5 points) You swing a weight attached to a string in a vertical circle. At the top of the circle the string just barely goes slack for an instant. At this point, the centripetal acceleration of the weight is a. Greater than g- b. Less than g. c. Equal to g- d. Can't answer without knowing the weight's speed