- #1

mkaa11

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**hi**

**i have an exam and i was trying solving old exams and i came upon this problem**

1. Homework Statement

1. Homework Statement

Due to air resistance, a 60- kg parachutist experiences an acceleration of 3.0 m/s2 while

falling in the air. If she falls 80 m in 12 seconds what is her final speed (in m/s)?

## Homework Equations

i know its a constant acceleration problem so

vf=vi+at

D=vit+0.5at^2

vf^2=vi^2+2aD

## The Attempt at a Solution

D is Y2-Y1 =(-80-0)=-80

by using 2nd equation vi=24.7

and then using 1st equation vf should be -11.3

so final speed should be 11.3

but when i checked the answer i found it different

here is the answer that i found

d=vt-1/2at^2

-80=12v-1/2(-3)(12)^2

v=24.7=25 m/s

final answer is 25