These forces create a horizontal torque on the gyroscope, which create a change in angular momentum L that is also horizontal.

Torque affects both the direction and the magnitude of angular momentum.

What is the direction of the angular momentum of a rotating object like the disk in Figure 1 The figure shows the right-hand rule used to find the direction of both angular momentum and angular velocity.

The right-hand rule defines both to be perpendicular to the plane of rotation in the direction shown.

Notice in the figure that both point along the axis of rotation.

The direction of angular velocity size and angular momentum L are defined to be the direction in which the thumb of your right hand points when you curl your fingers in the direction of the disks rotation as shown.

This result is illustrated in Figure 2, which shows the direction of torque and the angular momentum it creates.

Let us now consider a bicycle wheel with a couple of handles attached to it, as shown in Figure 3.

This device is popular in demonstrations among physicists, because it does unexpected things.) With the wheel rotating as shown, its angular momentum is to the womans left.

Suppose the person holding the wheel tries to rotate it as in the figure.

Her natural expectation is that the wheel will rotate in the direction she pushes itbut what happens is quite different.

The forces exerted create a torque that is horizontal toward the person, as shown in Figure 3(a).

This torque creates a change in angular momentum L in the same direction, perpendicular to the original angular momentum L, thus changing the direction of L but not the magnitude of L.

Figure 3 shows how L and L add, giving a new angular momentum with direction that is inclined more toward the person than before.

Figure (b) shows that the direction of the torque is the same as that of the angular momentum it produces.

This torque causes a change in angular momentum L in exactly the same direction.

Figure (b) shows a vector diagram depicting how L and L add, producing a new angular momentum pointing more toward the person.

The wheel moves toward the person, perpendicular to the forces she exerts on it.

Figure 4 shows the two forces acting on a spinning gyroscope.

The torque produced is perpendicular to the angular momentum, thus the direction of the torque is changed, but not its magnitude.

The gyroscope precesses around a vertical axis, since the torque is always horizontal and perpendicular to L.

If the gyroscope is not spinning, it acquires angular momentum in the direction of the torque ( L L ), and it rotates around a horizontal axis, falling over just as we would expect.

Its angular momentum is along its axis and points at Polaris, the North Star.

But Earth is slowly precessing (once in about 26,000 years) due to the torque of the Sun and the Moon on its nonspherical shape.

Gyroscopic Effect On Ship Pdf