Question

the purpose of safety devices like air bags and crash barriers is to

• increase the time to stop and increase the force.
• decrease the time to stop and increase the force.
• decrease the time to stop and decrease the force.
• increase the time to stop and decrease the force.

Explanation:

Step1: Relate force and momentum

$$F = \frac{\Delta p}{\Delta t}$$

Step2: Analyze safety device impact

$$\Delta t \uparrow \implies F \downarrow$$

Answer:

D. increase the time to stop and decrease the force.