Final answer:
To determine the number of hand brakes, we need to consider the distance and time it takes for the truck to stop. This can be done by recording the braking distance or the braking time when driving at a certain speed. These measurements can be used to calculate the number of hand brakes required.
Step-by-step explanation:
To determine the number of hand brakes, we need to consider the distance the driver covers before hitting the brakes, the time it takes for the truck to stop after hitting the brakes, and the total distance the truck covers to stop. One way to determine this is by driving the car at exactly 50 mph and applying the brakes until it stops, recording the distance it takes. Another approach is to drive the car at exactly 50 mph and apply the brakes until it stops, recording the time it takes. By using these measurements, we can calculate the braking distance and determine the number of hand brakes required.