What happens when you put a gyroscope inside a pendulum?

Question

Before my mind wandered away from physics years ago, this always bugged me. Does anyone have any idea how a gyroscope placed inside a swinging pendulum would affect the pendulum's motion? (if we assume that the gyroscope spins freely and the pendulum, while dropped along a straight path, is free to swing in any direction)

i'm not looking for a simplistic answer (of course, what seems to be the common sense answer may be anything but accurate, I'm not sure). I'm looking for something a little more specific and educated. The sad fact is, i'm just too busy, and too lazy to look into it myself.

Answer 1

It will stop the pendulum from swinging. The exact path of the pendulum while it is being brought to a stop will depend on the mounting of the pendulum (dual knife edge for swing in one plane or wire pivot which allows 3 D swing) and the mount of the gyroscope.
For one example, if the gyroscope is mounted rigidly to the head of the pendulum with the gyro axis in line with the pendulum line and the unit is pulled to one side before the gyro is spun up, when the device is released the pendulum will attempt to fall, will torque on the gyro and it will orbit around the hanging point at about the height of the originial release. A gyro is mounted on a gimbal so that it is total free to move relative to the pendulum head then it might swing with some interesting effects if both could be kept swinging (like the 50' long, 200# Foucault Pendulums in various museums.
http://www.sdnhm.org/about/pendulum.html
http://www.astro.louisville.edu/foucault/index.html

Answer 2

Inside or outside the pendulum? Depending on which one you mean, it would affect the motion in different ways. since you said inside, i will answer from that perspective first

1) the pendulum will make the gyroscope spin, and the gyroscope will increase the pendulum's inertia, which in turn, will make the pendulum swing either faster or farther than usual. However, it will not bring perpetual motion because of resistance.

Now, from the perspective on the outside...

2) same as one, except there is more air resistance, however, it may also increase inertia by spreading out the gravity of the pendulum. so these two forces will cancel out, making no affect whatsoever.

Answer 3

Because I am also too lazy to go into it (and may even have forgotten the math skills required) the gyroscope would force the pendulum swing out of planar motion into an elliptical cross section when viewed from above. A vertical cross section would probably still show some dip.