A car moving at 70km/h collides rams into an immobile steel wall. Its front of the is compressed by 0.94m . What average force must a seat belt exert in order to restrain a 75-kg passenger? I don't understand the answer which is given in this link http://oyc.yale.edu/sites/default/files/problem_set_3_solutions_2.pdf "Question 3"

Question

A car moving at 70km/h collides rams into an immobile steel wall. Its front of the is compressed by 0.94m . What average force must a seat belt exert in order to restrain a 75-kg passenger? I don't understand the answer which is given in this link http://oyc.yale.edu/sites/default/files/problem_set_3_solutions_2.pdf   "Question 3"

anonymous · Answer

it is simple. After the collision is complete the car comes to rest. during this time it travels a distance of 0.94 m. initially before collision it has a velocity of 70 Km/h. as it is coming to rest finally it has some decelration. force due to this decelration is nothing but the force with which man will also be experienced sitting in the car. hence seat Belt has to apply an equal and opposite force in order to restrain the person sitting in car.acceleration can be obtained like this. $$a=v ^{2}-u ^{2}/2*s$$ then Force= mass*Acceleration.

let me know if you have any further questions. Thanks

theraggedydoctor · Answer

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