An electric cargo bike is travelling along a cycle lane. The speed-time graph below shows the motion of Cargo Bike A. The rider of Cargo Bike A observes a pedestrian stepping into the path at time t=0.00 st = 0.00 \text{ s}t=0.00 s, and applies the brakes at t=0.80 st = 0.80 \text{ s}t=0.80 s. The bike comes to a complete stop at t=2.40 st = 2.40 \text{ s}t=2.40 s.
Show that the thinking distance is equal to the braking distance for Cargo Bike A by calculating both values from the graph.
Another cargo bike, Cargo Bike B, is also travelling at 16 m/s16 \text{ m/s}16 m/s. Its rider has a longer reaction time and applies the brakes at t=1.10 st = 1.10 \text{ s}t=1.10 s. Cargo Bike B decelerates at the same rate as Cargo Bike A. Determine the total stopping distance of Cargo Bike B.
The reaction time of a rider can be measured using a standard 30 cm30\text{ cm}30 cm ruler.
Explain how a ruler can be used to estimate reaction time.
State one precaution that must be taken to ensure the measurements are accurate and reliable.