(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

A person with a weight of 500N stands in an elevator on a scale.

from 0-5s his weight reads 500N.

from 5-10s his weight reads 700N.

from 10-15s his weight reads 500N.

from 15-20s his weight reads 300N.

Find his acceleration (in each time interval) and his velocity at 5s, 10s, 15s, and 20s.

3. The attempt at a solution

I think my accelerations are correct:

(Fn-mg) /m=a

0-5s: (500N-500N) / 51kg= 0m/s^2

5-10: (700-500)/51=3.92

10-15: (500-500)/51=0

15-20: 300-500/51= -3.92

Now, I think my velocities seem a little unreasonable.

vf=vi+at

at 5: v=0

10: v=0m/s + (3.92)(10)=39.2m/s <- that is really fast!

15: v=39.2m/s + (0)(15)= 39.2m/s

20: 39.2m/s+(-3.92)(20)= -39.2m/s

thanks for any help

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# Homework Help: Elevator force problem

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