Commentary: Cut to the chase: It's a matter of principle

The principle of moments, also known as Varignon's theorem, is a fundamental concept in physics and engineering that describes the equilibrium of a rigid body under the influence of external forces. The principle states that the moment of a force about a point is equal to the sum of the moments of the components of the force about the same point.
The moment is calculated by multiplying the magnitude of the force by the perpendicular distance from the point of application to the point about...

The principle of moments is a fundamental concept in physics and engineering. It refers to the balancing of forces and moments around a point or axis, also known as the pivot. This principle is used in many real-life scenarios, including construction, sports, and daily activities like opening doors and pushing objects.
One such scenario involves a pole placed in a three-dimensional system with a cable attached. When a tension is applied to the cable, the moment about the z-axis passing through...

According to Albert Einstein (1897-1955), free-falling and feeling weightless are intrinsically linked. If a person were in free-fall under gravity, for example, diving towards the Earth from an airplane, they would feel completely weightless. Similarly, a person descending in a lift may feel partially weightless. Broadly speaking, it is assumed that an object in a uniform gravitational field and an object undergoing constant acceleration in the absence of gravity are under the same...

When one considers a rigid body undergoing a plane motion, which is essentially a blend of translational and rotational movement, the application of Newton's second law gives the formula for the translational movement of such a body. If this equation is multiplied by a time interval, dt, and then integrated over the limits of integration, it results in an equation that embodies the principle of linear impulse.

The principle of virtual work is an essential concept in the field of mechanics and engineering. This is used to solve problems related to the equilibrium of a structure or system. It is based on the assumption that if a system is in equilibrium, the work done by all the forces during a virtual displacement is zero. This principle is applied by considering virtual displacements of the system and the corresponding work done by internal and external forces.
To apply the principle of virtual work,...

The angular impulse and momentum principle provides insights into how forces applied at a distance from an object's rotational axis influence its angular velocity. It builds upon the crucial relationship between the moment of force and angular momentum. By integrating this equation, substituting the limits for the initial and final times, a comprehensive expression representing the angular impulse and momentum principle is derived.