- #1

cidilon

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## Homework Statement

Marian, who is standing on her balcony, is surprised by a pigeon and throws a flowerpot up in the air at 2.1 m/s. It takes 3.0 s for the flowerpot to smash to the ground. The flowerpot experiences acceleration due to gravity of 9.81m/s2 [down].

a) How high is Marian's balcony?

b) How fast was the flowerpot moving just before it smashed to the ground?

v1= 2.1 [up]

a= -9.81m/s2 [up]

t= 3.0 s

## Homework Equations

Since acceleration is constant

d = v1*t + .5*a*t*t

v2[squared] = v1[squared] + 2*a*d

## The Attempt at a Solution

a)

First i used d = v1*t + .5*a*t*t

d = 2.1*3.0 + .5*-9.81*3.0*3.0

d = -37.8 m [up] or -38 m [up] ---> i round it to 2 sig figs here, right?

Now here is where i get confused.

This is negative displacement because the flower pot is flying most of it's way down to the ground. Right? What i am confused about is, is this the actual displacement from the balcony to the ground? Is Marian's balcony 38 m high?

It just seems not right to me for some reason, it feels like i am missing some sort of step.

If this is the answer, then for b) i use

v2[squared] = v1[squared] + 2*a*d

v2[squared] = 2.1[squared] + 2(-9.81)(-38)

v2[squared] = 749.97[square root]

v2 = 27.4 m/s or 27 m/s --->should i make it three or two figs. I think two figs, right?

If everything is correct so far, why do i have positive velocity instead of negative. Should it not be negative?

Thanks in advance and if i am totally wrong, please do correct me :)

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