# Period of a Sinusoidal Function

• Dec 16th 2012, 01:58 PM
sakonpure6
Period of a Sinusoidal Function
... At t= 1 the chair is closest to the wall and d(1) = 18cm . At t = 1.75s the chair is farthest from the wall and d (1.75) = 34cm. What is the period?

Is it 0.75s ? because the back of the book says 1.5s!
• Dec 16th 2012, 02:21 PM
skeeter
Re: Period of a Sinusoidal Function
I assume the chair moves from "close to the wall", then "far from the wall", then back "close to the wall" ... how much time to go from "close to the wall" back to "close to the wall" again?

that would be the period.
• Dec 16th 2012, 02:43 PM
sakonpure6
Re: Period of a Sinusoidal Function
so o.75 seconds right?
• Dec 16th 2012, 02:58 PM
skeeter
Re: Period of a Sinusoidal Function
no ...

t(close to wall) = 1

t(far from wall) = 1.75

t(back to close to the wall) = ?
• Dec 16th 2012, 03:07 PM
sakonpure6
Re: Period of a Sinusoidal Function
I don't get it... because let's assume that the at 0s it equals 18cm so it means that 0.75s it equals 34, which gives us a period of 0.75s ?!
• Dec 16th 2012, 03:09 PM
skeeter
Re: Period of a Sinusoidal Function
post the entire problem statement as it is presented to you, please.
• Dec 16th 2012, 03:21 PM
sakonpure6
Re: Period of a Sinusoidal Function
Quote:

Originally Posted by skeeter
post the entire problem statement as it is presented to you, please.

Megan is sitting in a rocking chair. The distance, d(t) between the wall and the rear of the chair varies sinusodally with time t. At t= 1s, the chair is closest to the wall and d(1)=18cm. At t=1.75s the chair is farthest from the wall and d(1.75)=34cm.
a) what is the period of the function?
• Dec 16th 2012, 03:24 PM
skeeter
Re: Period of a Sinusoidal Function
period is the time it takes to go back and forth one time ... that is called a complete cycle of motion.

.75 forth and .75 back = 1.5 seconds.