Question

The equation h = 7 cos (pi/3 t) models the height h in centimeters after t seconds of a weight attached to the end of a spring that has been stretched and then released.

Find the times at which the weight is at a height of 1 cm, of 3 cm, and of 5 cm below the rest position for the second time. Round your answers to the nearest hundredth.

Answer 1

any idea?

Answer 2

i think i have to find the iverse function to find t can you help?

Answer 3

nd so if h=1 you get t=3/πcos^−1(1/7)

Answer 4

about 1.36
http://www.wolframalpha.com/input/?i=3%2Fpi%28arccos%281%2F7%29

Answer 5

what about the 5?

Answer 6

that is where i get confused...

Answer 7

this the answer of A

Answer 8

A: π/3 cos^−1(h/7)

Answer 9

ok i think i got it thanks ;)

Answer 10

right typo there 3/π

Answer 11

you start at t=0 i believe, so rest position is 7

Answer 12

another screwy question
starts at 7, goes down to -7 and then back up to 7
it is never 1 above 7

Answer 13

it is litle bit confuse your exercice but it is like that i am sure

Answer 14

yeah it is confusing, but you really helped thanks!

Answer 15

let continue maybe i can do more for you ^^

Answer 16

more explaination
h = A*cos(Bt + C) + D

where D is some positive number to have this make sense (and not have negative heights)

Answer 17

actually, D > 7 for this to make complete sense

Answer 18

ok :D?

Answer 19

wait im so confused right now

Answer 20

you can imagine it touching the ground at the lowest point if D = 7

Answer 21

where did D come from?

Answer 22

i answered ;)

Answer 23

imagine that the lowest point if d=7

Answer 24

oh yeah ok i got now! i hadn't read everything you typed

Answer 25

've seen instances where

arcsine(y) = {x| sin(x) = y}

and sin^(-1) was the actual function

but it depends on the book really

Answer 26

i give you medal at least you understand i hope so ^^

Answer 27

yeah thanks! i will give you a medal for explaining throughly!
thanks sooo much!

Answer 28

thanks for the medal too! =D