• bhargav khanpara

MemberNov 1, 2013

## What is the difference among moment, torque and couple?

In physics, torque can informally be thought of as "rotational force". The SI units for Torque are newton meters although centinewton meters, foot-pounds force (ft·lbf), inch pounds (lbf·in) and inch ounces (ozf·in) are also frequently used expressions of torque. The symbol for torque is τ, the Greek letter tau. The concept of torque, also called moment or couple, originated with the work of Archimedes on levers.

In physics, the moment of force (often just moment, though there are other quantities of that name such as moment of inertia) is a quantity that represents the magnitude of force applied to a rotational system at a distance from the axis of rotation. The concept of the moment arm, this characteristic distance, is key to the operation of the lever, pulley, gear, and most other simple machines capable of generating mechanical advantage. The SI unit for moment is the newton meter (Nm).

Moment = Magnitude of Force x Perpendicular distance to the pivot (Fd)
Howdy guest!
Dear guest, you must be logged-in to participate on CrazyEngineers. We would love to have you as a member of our community. Consider creating an account or login.
Replies
• MemberNov 7, 2013

Are you sure? This action cannot be undone.
• MemberNov 7, 2013

Thanks.
Are you sure? This action cannot be undone.
• MemberNov 7, 2013

bhargav khanpara
In physics, torque can informally be thought of as "rotational force". The SI units for Torque are newton meters although centinewton meters, foot-pounds force (ft·lbf), inch pounds (lbf·in) and inch ounces (ozf·in) are also frequently used expressions of torque. The symbol for torque is τ, the Greek letter tau. The concept of torque, also called moment or couple, originated with the work of Archimedes on levers.

In physics, the moment of force (often just moment, though there are other quantities of that name such as moment of inertia) is a quantity that represents the magnitude of force applied to a rotational system at a distance from the axis of rotation. The concept of the moment arm, this characteristic distance, is key to the operation of the lever, pulley, gear, and most other simple machines capable of generating mechanical advantage. The SI unit for moment is the newton meter (Nm).

Moment = Magnitude of Force x Perpendicular distance to the pivot (Fd)
Moment - Static moment of some quantity, except the term "moment of inertia". Let us take a Steel I member. Two different types of moment takes place in the member there are "Major axis moment" & "Minor axis moment".

Torque - Its nothing but the "twisting or rotational moment". The cross product of a vector from some reference point to the point of application of the force with the force itself.

Couple - This is a force determined from the moment. (i.e.) Moment x lever arm
Are you sure? This action cannot be undone.
• MemberNov 8, 2013

However, "torque" tends to be used when there is an axle or pivot to be turned around, while "moment" tends to be used in essentially non-rotational situations, such as analysis of forces on a beam.

Read more: <a href="https://www.physicsforums.com" target="_blank" rel="nofollow noopener noreferrer">Physics Forums | Science Articles, Homework Help, Discussion</a>
Are you sure? This action cannot be undone.