In a vehicle suspension

Suspension (vehicle)

Suspension is the term given to the system of springs, shock absorbers and linkages that connects a vehicle to its wheels. Suspension systems serve a dual purpose — contributing to the car's roadholding/handling and braking for good active safety and driving pleasure, and keeping vehicle occupants...

, roll moment is the moment of inertia

Moment of inertia

In classical mechanics, moment of inertia, also called mass moment of inertia, rotational inertia, polar moment of inertia of mass, or the angular mass, is a measure of an object's resistance to changes to its rotation. It is the inertia of a rotating body with respect to its rotation...

 of the vehicle's sprung mass

Sprung mass

In a vehicle with a suspension, such as an automobile, motorcycle or a tank, sprung mass is the portion of the vehicle's total mass that is supported above the suspension, including in most applications approximately half of the weight of the suspension itself...

 (the portion of its weight supported by the suspension). The roll moment is the product of the sprung mass and the square of the distance between the vehicle's roll center

Roll center

The roll center of a vehicle is the notional point at which the cornering forces in the suspension are reacted to the vehicle body.-Theory:There are two definitions of roll center...

 and its center of mass

Center of mass

In physics, the center of mass or barycenter of a system is the average location of all of its mass. In the case of a rigid body, the position of the center of mass is fixed in relation to the body...

. If the vehicle is subjected to centrifugal force

Centrifugal force

Centrifugal force can generally be any force directed outward relative to some origin. More particularly, in classical mechanics, the centrifugal force is an outward force which arises when describing the motion of objects in a rotating reference frame...

s, such as in a turn, the roll moment will cause the body to rotate (lean) towards the outside of the turn.

In aeronautics

Aeronautics

Aeronautics is the science involved with the study, design, and manufacturing of airflight-capable machines, or the techniques of operating aircraft and rocketry within the atmosphere...

, the roll moment is the aerodynamic force

Force

In physics, a force is any influence that causes an object to undergo a change in speed, a change in direction, or a change in shape. In other words, a force is that which can cause an object with mass to change its velocity , i.e., to accelerate, or which can cause a flexible object to deform...

 applied at a distance from an aircraft's center of mass that causes the aircraft to undergo angular acceleration

Angular acceleration

Angular acceleration is the rate of change of angular velocity over time. In SI units, it is measured in radians per second squared , and is usually denoted by the Greek letter alpha .- Mathematical definition :...

 about its roll axis. The roll axis is usually defined as the longitudinal axis, which runs from the nose to the tail of the aircraft. A roll moment can be the result of wind gusts, control surfaces such as ailerons, or simply by flying at an angle of sideslip. See flight dynamics

Flight dynamics

Flight dynamics is the science of air vehicle orientation and control in three dimensions. The three critical flight dynamics parameters are the angles of rotation in three dimensions about the vehicle's center of mass, known as pitch, roll and yaw .Aerospace engineers develop control systems for...

.