Final answer:
The idiom 'slower than molasses in winter' signifies a slow process due to increased molecular interactions and viscosity of molasses in cold temperatures, mirroring why a warm car engine is more fuel efficient than a cold one.
Step-by-step explanation:
The idiom 'slower than molasses in winter' is a vivid description of a process that occurs very slowly. Molasses is a thick, sticky syrup that flows sluggishly, especially in cold temperatures. The changing temperature affects molasses because, as the temperature decreases, the molasses' molecular interactions increase due to decreased kinetic energy. This makes it thicker and more viscous, causing it to flow more slowly. The molecules of molasses are large and have a complex shape, which means they cannot move past each other easily at low temperatures. Similarly, a cold car engine is less fuel efficient because the oil inside becomes more viscous in lower temperatures, which increases the engine's internal friction. Upon warming up, the oil thins, internal parts move more freely, and combustion becomes more efficient, thereby improving the engine's fuel efficiency