A 2200-kg sport utility vehicle traveling at 86 km/h can be stopped in 0.17 s if

Question

A 2200-kg sport utility vehicle traveling at 86 km/h can be stopped in 0.17 s if it hits a concrete wall. Assume a 60 kgperson was in the car that hit this wall. The velocity of theperson equals that of the car both before and after the crash, andthe velocity changes in 0.17 s. (a) What is the average force exerted on theperson?
1 N (in a directionopposite to the initial motion)

(b) Some people think that they can stop themselves rushing forwardby putting their hands on the dashboard. Find the mass of theobject that has a weight equal to the force you justcalculated.
2 kg

Could you lift such a mass? Are you strong enough to stop yourselfwith your arms?
3 (a) What is the average force exerted on theperson?
1 N (in a directionopposite to the initial motion)

(b) Some people think that they can stop themselves rushing forwardby putting their hands on the dashboard. Find the mass of theobject that has a weight equal to the force you justcalculated.
2 kg

Could you lift such a mass? Are you strong enough to stop yourselfwith your arms?
3

Explanation / Answer

force on the person                            F = mv / t           v = intial - final velocity                = (85000 /3600) m /sec            m = mass of the person              t= time of impact = 0.17sec             from the above relation we can solve for ' F '           mass of the equivalent force experienced by the personin the car                     m = F /g an average person lift a weight = 150kg           whether he can bare a force depends on equivalent mass ' m 'calculated

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