Question

If you see a bicyclist on the road ahead with his or her left arm extended downward to the left, you should assume the bicyclist is ____.

1) Turning left
2) Stopping
3) Changing lanes to the left
4) Signaling a right turn

Answer 1

A bicyclist with their left arm extended downward is signaling that they are stopping. The subject deals with physical motion and motorcycle dynamics, specifically stationary reference frames and countersteering.

Step-by-step explanation:

If you see a bicyclist on the road ahead with his or her left arm extended downward to the left, you should assume the bicyclist is stopping. This is because in bicycle hand signals, an extended arm can mean different actions depending on its position. A left arm extended out horizontally usually indicates a left turn. However, if the left arm is extended downward, it typically signifies that the bicyclist is signaling a stop.

To address the questions from the physics context, they are related to subjects of motion and dynamics within a reference frame and the mechanics of motorcycle turning:

1. While standing on a sidewalk facing the road, in the reference frame of a bicyclist passing by, you are stationary with respect to the bicyclist.
2. When a physics student driving a motorcycle at highway speed pulls back lightly on the right handlebar causing the cycle to tip to the left and subsequently turn left, this happens due to countersteering, a method used to initiate a turn for a two-wheeled vehicle.

Without seeing Figure 3.6, it is difficult to interpret the described road signage. However, it is generally advised to familiarize oneself with international and local road sign conventions to correctly interpret various signs while driving.