# Homework Help: Pendulum question

1. Feb 5, 2010

### zhenyazh

A pendulum has a length L = 1.07 m. It hangs straight down in a jet plane about to take off The jet accelerates uniformly, and during that time, the pendulum oscillates about the equilibrium position to a maximum distance D = 0.370 m. Calculate the magnitude of the plane's acceleration.

so as i understand if the plane starts moving to the left, the pendulum is thrown to the right.
its acceleration is the acceleration of the plane.
the acceleration at the farthest point is a=-A*w^2*cos(wt).
where the cos is 1 A is either D or the angular distance and w is the ratio between the roots
of g and l.
but i am wrong.
where am i wrong.

2. Feb 5, 2010

### thebigstar25

you are starting well by saying that the acceleration of the plane is same as the pendulum ..

mmm but im not sure why you didnt take the easy way ..

as you are suggesting if the plane is moving to the left then the pendulum is moving to the right .. I made this figure :

http://img407.imageshack.us/img407/7069/78208931.jpg [Broken]

I think with the information in the figure along with newton`s 2nd law in the x- and y- directions you can get the acceleration .. does what i say make sense? .. :)

Last edited by a moderator: May 4, 2017