Aperson who is properly constrained by an over-the-shoulder seat belt has a good chance of surviving a car collision if the deceleration does not exceed about 30 "gs" (1.0 g = 9.8 m/s^2). assuming uniform deceleration of this value, what is the distance over which the front end of the car must be designed to collapse if a crash brings the car to rest from 75 km/h?

Distance = 0.738 m

Explanation:

Solution:  

First convert Km/h into m/s.  

75 km/h * 1000 m/km * 1 hr/3600 sec = 20.8333 m/s  

According to third equation of motion:

– = 2 * acceleration * distance

Vf= final velocity

Vi= initial velocity

putting values in third equation of motion....

– = 2 * (-30 * 9.8) * distance

note:

negative sign is due to deceleration

Distance = 0.738 m

the motion of a pendulum is a classic example of mechanical energy conservation. a pendulum consists of a mass (known as a bob ) attached by a string to a pivot point. as the pendulum moves it sweeps out a circular arc, moving back and forth in a periodic fashion.

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