Question

how does an airbag help protect a passenger in a car following a car accident? it shortens the passengers stopping time, and this decreases the force. it shortens the passengers stopping time, and this increases the force. it increases the passengers stopping time, and this decreases the force. it increases the passengers stopping time, and this increases the force.

Explanation:

According to the impulse - momentum theorem $F\Delta t=\Delta p$. In a car accident, the change in momentum $\Delta p$ of the passenger is fixed. When the air - bag deploys, it increases the time $\Delta t$ it takes for the passenger to come to a stop. Since $F = \frac{\Delta p}{\Delta t}$, when $\Delta p$ is constant and $\Delta t$ increases, the force $F$ acting on the passenger decreases, thus protecting the passenger.

Answer:

It increases the passenger’s stopping time, and this decreases the force.