Momentum related question

by milkyway11
Tags: impulse, momentum
milkyway11 is offline
Feb13-11, 05:46 PM
P: 16
question states: a 1980 kg car moving at 13 m/s is brought to a stop in 2 seconds when it collides with a wall. if a new model of this car has a longer crumple zone, the passengers experience a 3217.5 N force upon impact. by what percentage has the period of impact been increased? has the impulse on the car and its passengers changed.

my attempt at this problem is to find the new model's acceleration by use F=ma, then use the kinematics Vf=Vo+at to find the period to be 8 sec. Then I can calculate the percentage by dividing the difference with the original period. But this somehow seemed to easy and I am not sure if it's right. Also, I would assume the impulse doesn't change since P=mv, but I am not sure on this.
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tiny-tim is offline
Feb14-11, 01:44 PM
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hi milkyway11! welcome to pf!

yes, your method looks fine (and yes, the impulse doesn't change)
milkyway11 is offline
Feb17-11, 04:52 PM
P: 16
Thank you!

Quote Quote by tiny-tim View Post
hi milkyway11! welcome to pf!

yes, your method looks fine (and yes, the impulse doesn't change)

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