1. The diagram below shows the acceleration of blood in the vasculature versus time in seconds. Give the time at which the blood is moving with the maximum velocity. Explain your answer.

2. All modern elevators feature safety mechanisms. For example, if an elevator cable breaks, the falling elevator car will land on a set of giant springs on the bottom of the shaft, compressing them. However, the conservation of energy asserts that the energy required to break the car's fall is the same whether the springs are present or not. How, then, do the springs save lives? (Be specific-what quantities are changed when the springs are present? Which of these explains the difference?)