Final answer:
Motorcyclists perform a shoulder check to safely assess their blind spots before turning. The physics behind a motorcycle turning when pulling back on the right handlebar involves the gyroscopic effect, countersteering, and angular momentum, resulting in the motorcycle leaning and turning towards the opposite side.
Step-by-step explanation:
Motorcyclists will often look over their shoulder before turning to perform a safety check, commonly known as a 'shoulder check' or 'head check'. This action is necessary to check the motorcycle's blind spots, areas that cannot be directly observed by the rider through the mirrors.
The shoulder check is a critical safety measure to ensure that other vehicles, particularly in adjacent lanes, are not in the path the motorcyclist intends to take. Additionally, in the context of physics, when a physics student notices that pulling back lightly on the right handlebar tips the cycle to the left and produces a left turn, this is due to the gyroscopic effect, coupled with a phenomenon known as countersteering.
To explain the physics behind this, when the motorcyclist pulls back on the right handlebar, they are initiating a countersteer.
This subtle movement causes the front wheel to steer briefly to the right. Due to the angular momentum of the wheels and the gyroscopic effect, the motorcycle then begins to lean to the left, and the balance of forces creates a leftward turn. The linear acceleration of the motorcycle is accompanied by an angular acceleration of its wheels, which together enable the turn. As the motorcycle leans, centripetal force is generated, maintaining the turn.