5.55 A 60 kg person is in a head-on collision. The cars speed at impact is 15 m/

Question

5.55

A 60 kg person is in a head-on collision. The cars speed at impact is 15 m/s. Express your answer using two significant figures. Problem 5.55 Estimate the net force on the person if he or she is wearing a seat belt and if the air bag deploys. Seat belts and air bags save lives by reducing the forces exerted on the driver and passengers in an automobile collision. Cars are designed with a 'crumple zone" in the front of the car. In the event of an impact, the passenger compartment decelerates over a distance of about 1 m as the front of the car crumples. An occupant restrained by seat belts and air bags decelerates with the car. By contrast, an unrestrained occupant keeps moving forward with no loss of speed (Newton's first law!) until hitting the dashboard or windshield. These are unyielding surfaces, and the unfortunate occupant then decelerates over a distance of only about5 mm Submit My Answers Give Up Part B Estimate the net force that ultimately stops the person if he or she is not restrained by a seat belt or air bag. Express your answer using two significant figures. et Submit My Answers Give Up Part C What is the force in part A in terms of the person's weight? Express your answer using two significant figures. Fnet Submit My Answers Give Up Part D What is the force in part B in terms of the person's weight? Express your answer using two significant figures. 0] ? Fnet

Explanation / Answer

A) Average force = ma

= m* v^2/2s

= 60*15^2 /(2*1)

= 6750 N

In two significant Figure F = 6.8*10^3 N

B) Average Force = ma = mv^2/2s

= 60*15^2 /(2*0.005)

= 1350000 N

In two significant Figure F = 1.4*10^6 N

C) Fnet/W =6750/(60*9.8) = 11 answer

D) Fnet/W = 1350000/(60*9.8) = 2.3*10^3 answer

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