Final answer:
A motorcycle rider should lean with the motorcycle to safely execute a turn. The rider initiates a lean by countersteering, causing the motorcycle to tip and the centripetal force to guide the turn. The wheels' angular momentum also plays a vital role in stabilizing the motorcycle during the turn.
Step-by-step explanation:
To execute a turn safely, a motorcycle rider should always lean with the motorcycle. This is a fundamental aspect of motorcycle dynamics. When a physics student, driving their motorcycle at highway speed, pulls back lightly on the right handlebar, the motorcycle tips to the left and initiates a left turn. This occurs due to a phenomenon called countersteering. By pushing on the right handlebar, a torque is generated which causes the motorcycle to lean to the left due to the gyroscopic effect of the wheels. This left-leaning causes the centripetal force needed to make the left turn.
Motorcycles turn by leaning into a turn, which aligns the force of the ground on the wheel to be in a line through the center of gravity. This alignment allows the centripetal force to act upon the motorcycle without overturning it. When the angular momentum of the wheels is considered, it becomes clear that for gyroscopes - like those in guidance systems - the direction of their angular momentum remains constant because they are precision engineered to resist changes in orientation due to external forces and accelerations, allowing them to maintain a consistent direction in space.