R = distance
dr/dt speed or with a direction, velocity
d(dr/dt)/dt = the time derivative of the velocity is called acceleration.
Speed is a scalar. Acceleration is a vector.
Answer:
Engineers can design a train with a regenerative braking system
Explanation:
Assuming the point of the question is that the engineers want to focus on using energy efficiently when starting and stopping, they would likely want to consider a regenerative braking system. Such a system can store energy during braking so that it can be used during starting, reducing the amount of energy that must be supplied by an outside power source.
