4. A car's air bag reduces forces during a collision by Increasing the change in velocity decreasing the car's mass Increasing the time of the change in momentum decreasing the time of the change in momentum

## Step 1<br />The problem is about the function of an airbag in a car during a collision. The airbag is a safety feature in cars that is designed to reduce the forces experienced by the occupants during a collision.<br /><br />## Step 2<br />The airbag works by increasing the time over which the change in momentum occurs. This is based on the impulse-momentum theorem, which states that the change in momentum of an object is equal to the impulse applied to it.<br /><br />### **Impulse = Change in Momentum**<br /><br />## Step 3<br />Impulse is the product of the force and the time over which the force is applied. By increasing the time over which the change in momentum occurs, the airbag reduces the force experienced by the occupants.<br /><br />## Step 4<br />The other options, such as increasing the change in velocity, decreasing the car's mass, and decreasing the time of the change in momentum, do not accurately describe the function of an airbag.