A toy freight train consists of an engine and three identical cars. The train is moving to the right at constant speed along a straight, level track. Three spring scales are used to connect the cars as follows: spring scale $A$ is located between the engine and the first car; scale $\mathrm{B}$ is between the first and second cars; scale $\mathrm{C}$ is between the second and third cars. Ignore the weights of the scales. (a) If air resistance and friction are negligible, what are the relative readings on the three spring scales $\mathrm{A}, \mathrm{B},$ and $\mathrm{C} ?$ (b) Repeat part (a), taking air resistance and friction into consideration this time. [Hint: Draw an $\mathrm{FBD}$ for the car in the middle.] (c) If air resistance and friction together cause a force of magnitude $5.5 \mathrm{N}$ on each car, directed toward the left, find the readings of scales $\mathrm{A}, \mathrm{B},$ and $\mathrm{C}$.