A 2200-kg sport utility vehicle traveling at 82 km/h can be stopped in 0.16 s if

Question

A 2200-kg sport utility vehicle traveling at 82 km/h can be stopped in 0.16 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 0.16 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


IF YOU GIVE ME THE CORRECT ANSWERS I WILL RATEYOU LIFESAVER!!!
(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


IF YOU GIVE ME THE CORRECT ANSWERS I WILL RATEYOU LIFESAVER!!!

Explanation / Answer

We can use F=ma to solve this problem.
For this problem we are only interested in what happens to theperson. So for part a, we can do the following: 60km/hr * 1000m/1km * 1hr/3600s = 16.67m/s a = v/t = (0m/s - 16.67m/s) / .16s =-104.19m/s2 F = ma F = 60kg * -104.19m/s2 F = -6251.25N For part b: We use F=ma again, only this time we substitute theacceleration due to gravity, g, for a: -6251.25N = -9.81m/s2 * m m = 637.23kg Would you be able to lift something that heavy? Considering there are about 2.2pounds per kilogram that is morethan half a ton. No, you would not be able to stop yourselfwith your arms. Would you be able to lift something that heavy? Considering there are about 2.2pounds per kilogram that is morethan half a ton. No, you would not be able to stop yourselfwith your arms.

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