Final answer:
Always check for motorcycles due to their smaller size and ease of being overlooked. Countersteering, a physics concept, shows why motorcycles tip opposite the direction of a turn initiation when at highway speeds.
Step-by-step explanation:
Before changing lanes or making a left turn, it is crucial to look carefully for motorcycles because they have a smaller profile than cars, making them less visible and more easily overlooked. This is important for safety when driving and is related to a concept in physics known as countersteering, which is when a rider initiates a turn. For example, pulling back on the right handlebar will cause the motorcycle to tip to the left and subsequently produce a left turn due to the gyroscopic effect and the redistribution of centripetal forces during countersteering.