A driver wearing a seatbelt decelerates at roughly the same rate as the car itse

Question

A driver wearing a seatbelt decelerates at roughly the same rate as the car itself. Since modern cars have a "crumple zone" built into the front of the car, the car will decelerate over a distance of roughly 1.2 m . Find the net force acting on a 70-kg driver who is decelerated from 22 m/s to rest in a distance of 1.2 m. Please show all the steps.

Part B

A driver who does not wear a seatbelt continues to move forward with a speed of 22 m/s (due to inertia) until something solid is encountered. The driver now comes to rest in a much shorter distance-perhaps only a centimeter. Find the net force acting on a 70-kg driver who is decelerated from 22 m/s to rest in 1.0 cm. Please show all the steps.

Explanation / Answer

PART A -
Distance = 1.2 m
Initial Velocity = 22 m/s
Final Velocity = 0
Acceleartion = a
V^2 = u^2 - 2*a*s
a = 22^2/(2*1.2)
a = 201.6 m/s^2

Force = Mass * Acceleration
Force = 70 * 201.6 N
Force = 14112 N
Force acting acting on a Driver, F = 14112 N

PART B -
Now,
Distance = 1.0 * 10^-2 m
Initial Velocity = 22 m/s
Final Velocity = 0

Deceleartion = a
V^2 = u^2 - 2*a*s
a = 22^2/(2*1.0 * 10^-2)
a = 24,200 m/s^2

Force = Mass * Acceleration
Force = 70 * 24,200 N
Force = 1694000 N
Force acting acting on a Driver, F = 1694000 N

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