Name: earth’s rotation and the coriolis effect
Uploaded: 2025-05-22T09:06:09.000Z
Duration: 1 min 23 s
Channel: JoVE

K12 Standards

Georgia Standards of Excellence

9-12

Oceanography

SO4.

SO4.2

Coriolis Force

A ball sliding on a turntable follows a straight-line trajectory. The force acting on the object in this inertial frame equals the product of mass and acceleration.
When the turntable starts rotating counterclockwise, the sliding ball&#39;s trajectory changes. The equation of motion in this non-inertial frame is modified to include the particle&#39;s acceleration in the rotating reference frame.
Fictitious forces, including Coriolis and centrifugal forces, act additionally in a rotating frame modifying the equation of motion.
The Coriolis force is proportional to the cross-product of the rotating frame&#39;s angular velocity and the object&#39;s velocity.
The cross-product right-hand rule gives the direction of the Coriolis force. Consider the palm of the right hand aligning along the rotating frame&#39;s angular velocity, and the fingers curl toward the object&#39;s velocity. The thumb points opposite the Coriolis force, as indicated by the negative sign in the Coriolis force expression.
So, a ball in a counterclockwise rotating turntable follows a circular trajectory toward the right. If the table rotates clockwise, the ball deflects toward the left.

coriolis force

An accelerating particle experiences a force equal to the mass multiplied by the acceleration in an inertial frame of reference. Consider a particle in a non-inertial frame of reference, such as a sliding ball on a rotating table. The acceleration of the ball in this rotating reference frame is different than in the intertial frame, which modifies its equation of motion. The fictitious forces acting additionally on a rotating frame of reference alter Newton&#39;s Second Law expression. Centripetal and Coriolis forces are the fictitious or pseudo forces that act on a particle in a non-inertial frame of reference.
The discovery of the Coriolis force dates back to 1651 when Italian military officers reported that, during artillery practice, the cannon balls always landed to the right of where the calculations predicted. The Coriolis force is named after a French mathematician Gaspard Gustave Coriolis (1792&#8211;1843) for his work in the field of rotating reference frames.
The Coriolis force is proportional to the cross-product of the rotating frame&#39;s angular velocity vector and the object&#39;s velocity vector. Its direction can be estimated using the right-hand rule for the cross-product. Suppose the index finger and thumb are directed toward the object&#39;s velocity and the rotating frame&#39;s angular velocity, respectively. The middle finger points opposite to the Coriolis force, as indicated by the negative sign in the Coriolis force expression. The work done by Coriolis force is zero since it always acts perpendicular to the object&#39;s motion.
Due to the Earth&#39;s rotation, the Coriolis force tends to deflect moving bodies toward the right in the northern hemisphere and toward the left in the southern hemisphere. As a result, long-range snipers aim to the left of their target in the northern hemisphere.
The Coriolis force also results in cyclone formation. In the northern hemisphere, air rushing out of a high-pressure system swirls clockwise around the pressure center. Similarly, air flowing into a low-pressure region swirls counterclockwise. The turn direction of the swirling is opposite in the southern hemisphere due to the Coriolis force. The Coriolis force is zero at the equator, and as a result, no cyclones occur at the equatorial axis.

An accelerating particle experiences a force equal to the mass multiplied by the acceleration in an inertial frame of reference. Consider a particle in a ...

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Education

JoVE Core

Physics

Unit 1

Rotation and Rigid Bodies

KEY TERMS AND CONCEPTS

earth’s rotation and the coriolis effect

Earth’s rotation creates the Coriolis force, a pseudo force seen in rotating reference frames. It helps explain why motion looks different on a spinning surface than it does in an inertial frame, where Newton’s second law is written in its usual form. A sliding ball on a rotating table is one example of this change in motion.

In a non-inertial frame, fictitious forces must be added to the motion of an object. Centripetal force and Coriolis force are the two pseudo forces that act on a particle in a rotating system. The Coriolis force was first noticed in 1651, when Italian military officers reported that cannon balls landed to the right of the predicted spot during artillery practice.

The force is named after French mathematician Gaspard Gustave Coriolis, who studied rotating reference frames. It is proportional to the cross-product of the frame’s angular velocity vector and the object’s velocity vector. The right-hand rule shows its direction. If the index finger points along the object’s velocity and the thumb points along the angular velocity, the middle finger points opposite the Coriolis force because of the negative sign in the equation.

Coriolis force does no work because it acts perpendicular to the object’s motion. On Earth, it deflects moving bodies to the right in the northern hemisphere and to the left in the southern hemisphere. This is why long-range snipers in the northern hemisphere aim to the left of the target. The force also helps shape cyclone motion. In the northern hemisphere, air around a high-pressure system turns clockwise, and air into a low-pressure region turns counterclockwise. The pattern reverses in the southern hemisphere. At the equator, the Coriolis force is zero, so cyclones do not form on the equatorial axis.

Earth’s Rotation and the Coriolis Effect

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/files/media/science-education/science-education-thumbs/14741.jpg

Earth’s rotation creates the Coriolis force, a pseudo force seen in rotating reference frames. It helps explain why motion looks different on a spinning surface than it does in an inertial frame, where Newton’s second law is written in its usual form. A sliding ball on a rotating table is one example of this change in motion. In a non-inertial frame, fictitious forces must be added to the motion of an object. Centripetal force and Coriolis force are the two pseudo forces that act on a particle...

key terms and concepts

Learn how Earth’s rotation creates the Coriolis force, why motion changes in rotating frames, and how it affects cannon fire, winds, and cyclones.

Earth’s Rotation and the Coriolis Effect | JoVE K12

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Earth’s Rotation and the Coriolis Effect

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