Question

a 5.0kg rock is dropped from rest down a vertical

mine shaft. How long does it take for the rock to

reach a depth of 79m? Neglect air resistance

Answer 1

seems like this is similar to the last question, right?

Answer 2

yes, the only difference is we need to find the acceleration

Answer 3

ahh

Answer 4

so our x=7.9, right?

Answer 5

I mean 79

Answer 6

x?

Answer 7

x=x initial-Voxt

Answer 8

oh wait

Answer 9

x=x initial+voxt+1/2gt squared right?

Answer 10

aah
wait, we dont need to find the acceleration , it will also be a=9.8 m/s^2(down)
i think, give me a sec. i'll try to do it on my own

Answer 11

or is it no longer gravitiy?

Answer 12

yeah, you're right
we will use that formula

Answer 13

ok

Answer 14

the mass almost got me XD

Answer 15

so 79=x initial+voxt+1/2gt squared

Answer 16

so does voxt=5.0kg?

Answer 17

thanks for helping me by the way

Answer 18

5 kg---> is the mass of the object, they just write it to confused you (like me)

\(v_o= 0\ m/s\) so like before, it will cancel out

Answer 19

*confuse

Answer 20

so x0=0 as well?

Answer 21

and if that is the case, I get 4.9t squared+t=79

Answer 22

or better yet

Answer 23

4.9t squared+t-79=0

Answer 24

xo is the initial position right?
sorry i'm using different variables, that's why i ask.

yes you're right again ;p

Answer 25

and if that is the case, my answer is rounded to approximately 3.9

Answer 26

which is approximately 4.0s

Answer 27

and that is the answer!!!!!

Answer 28

yeah, i got approx 4.02s

Answer 29

x0 is initial position

Answer 30

next problem?

Answer 31

okay, i'll stay until 10 pm XD

Answer 32

ty so much

Answer 33

np :)

Answer 34

you be a lifesaver

Answer 35

whoa, lowl, thanks!
you will be too! :)