# physics

posted by
**kate** on
.

A rule of thumb for automobile collisions against a rigid barrier is that the collision lasts about .11 seconds, for any initial speed and for any model of automobile. accordingly, the deceleration experienced by an automobile during a collision is directly proportional to the change of velocity (delta v) (with a constant factor of proportionality), and therefore (delta v) can be regarded as a measure of the severity of the collision.

a. if the collision lasts .11 seconds, what is the average deceleration experienced by an automobile in an impact on a rigid barrier at 55 km/hr? 65 km/h? 75km/h?

b. for each of these speeds, what is the crush distance of the front end of the automobile? assume constant deceleration for this calculation.

c. for each of these speeds, what is the average force the seat belt must exert to hold a driver of 75 kg in his seat during the impact.