Department of Energy Argonne National Laboratory Office of Science NEWTON's Homepage NEWTON's Homepage
NEWTON, Ask A Scientist!
NEWTON Home Page NEWTON Teachers Visit Our Archives Ask A Question How To Ask A Question Question of the Week Our Expert Scientists Volunteer at NEWTON! Frequently Asked Questions Referencing NEWTON About NEWTON About Ask A Scientist Education At Argonne Gyroscope Precession
Name: Mike D.
Status: student
Age: 17
Location: N/A
Country: N/A
Date: 8/26/2004

Is the right-hand rule for angular momentum of a gyroscope dependent on the hemisphere in which the gyroscope is spinning? If not, why does the gyroscope have angular momentum in one direction with no other variables influencing it?

To clarify, when I have a bike wheel on a peg, vertically, in front of me and I spin it clockwise from the perspective of someone to the right of me, why does the wheel turn to my left?

In space, does a gyroscope act this same way? With no other variables to influence the gyroscope, why would it turn one way and not the other?

Mike D.,

The direction of precession depends on the direction the wheel is spinning, not the hemisphere.

Angular momentum and torque work together in the same way as linear momentum and force. Force, a linear push, causes momentum to change. Torque, a twisting push, causes angular momentum to change. Also, angular momentum points along the axis of rotation. Torque points along the axis about which it twists.

In some ways, this gyroscope effect is similar to the force and momentum of a rock on a string. The rock spins in a circle. Momentum is tangent to the circle. Force due to the string is toward the center, perpendicular to the circle. The momentum keeps rotating in the direction of force, but force keeps rotating as well. All momentum can do is keep rotating.

Consider a gyroscope on its side, pointing toward you. You see the gyroscope as spinning counter-clockwise. The angular momentum vector points right at you. Gravity tries to make the top of the gyroscope move downward. The torque must then be perpendicular to the gyroscope axis. Torque due to gravity points to the right. The angular momentum is then pulled a little to the right by this torque. As the gyroscope rotates, so does the torque axis. The angular momentum never gets a chance to line up with the torque. All the angular momentum can do is continuously rotate toward the direction of the torque.

Gyroscopes would do nothing in outer space. With no gravity to exert the torque, there would be no reason for angular momentum to change direction. The spinning gyroscope would not turn.

Dr. Ken Mellendorf
Physics Instructor
Illinois Central College

Click here to return to the Physics Archives

NEWTON is an electronic community for Science, Math, and Computer Science K-12 Educators, sponsored and operated by Argonne National Laboratory's Educational Programs, Andrew Skipor, Ph.D., Head of Educational Programs.

For assistance with NEWTON contact a System Operator (, or at Argonne's Educational Programs

Educational Programs
Building 360
9700 S. Cass Ave.
Argonne, Illinois
60439-4845, USA
Update: June 2012
Weclome To Newton

Argonne National Laboratory