Question

Find out the reason why an airbag reduces injury to a passenger during a car crash.

• A. The air bag reduces the force by reducing the passengers change in velocity.
• B. The air bag reduces the change in momentum by increasing the passengers impulse.
• C. The air bag reduces the impulse by reducing the change in the passengers momentum.
• D. The air bag reduces the force by increasing the time it takes the passenger to stop moving.
• E. The air bag reduces the change in velocity by reducing the time it takes the passenger to stop moving.

Answer 1

The correct option is D The air bag reduces the force by increasing the time it takes the passenger to stop moving.

We have

Impulse $I=F\times t=$change in momentum

or $F=$change in momentum /$t$ ...........$eq\left(1\right)$

or in a vehicle after an accident , passenger stops finally so its final momentum is zero

Change in momentum $\Delta p=0-mv=-mv$ where $v$ is initial velocity

It shows that change in momentum is constant ,so air bag increases the time of impact so that force decreases.