Question

Question #1fbad

Answer 1

Newton's 2nd Law

Explanation:

Newton's 2nd law tells us that the force on an object is equal to its rate of change of momentum

`F=(mv-"mu")/t=ma`

Where `m` is the mass, `v` the final velocity, `u` is the initial velocity, `t` is the time the force is applied for (and `a` is acceleration).

So in a collision that brings a car to a stop (`v`=0)
`F=-"mu"/t`

In a collision, we want to reduce the force on a person. Hence by the above equation, we can do this in 2 ways - reducing our initial speed or increasing the time of the force being applied.

The seat belt increases the time. It does this by stretching during the collision, thereby extending the time the force is applied to the person.