# pendulum problem?

A pendulum has a length L = 1.00 m. It hangs straight down in a jet plane about to take off as shown by the dotted line in the figure. The jet accelerates uniformly, and during that time, the pendulum oscillates about the equilibrium position shown by the solid line, with D = 0.400 m. Calculate the magnitude of the plane's acceleration . ( http://uae4up.com/uploads/cb6c6cf3dd.gif )

### 2 Answers

- 1 decade agoFavorite Answer
If the pendulum were stationary, its acceleration at this point would perpendicular to L and be given as:

sin(theta) = D/L

sin(theta) = 0.4/1

theta = 23.58 deg

a = g*sin(theta)

a = 9.8*0.4

a = 3.92

The to keep the equilibrium point here, the jet's acceleration must be equal to the x component of this acceleration:

a_x = a*cos(theta)

a_x = 3.92*cos(23.58)

a_x = 3.59 m/sec^2