Category: Equilibrium and Elasticity

When a large number of atoms come together to form a metallic solid, such as an iron nail, they settle into equilibrium positions in a three-dimensional lattice, a repetitive arrangement in which each atom is a well-defined equilibrium distance from its nearest neighbors. The atoms are held together by interatomic forces that are modeled as tiny springs…

For the problems of this lesson, we have only three independent equations at our disposal, usually two balance of forces equations and one balance of torques equation about a given rotation axis. Thus, if a problem has more than three unknowns, we cannot solve it. It is easy to find such problems. In Sample Problem 12-2,…

In this section we examine four sample problems involving static equilibrium. In each, we select a system of one or more objects to which we apply the equations of equilibrium (Eqs. 12-7, 12-8, and 12-9). The forces involved in the equilibrium are all in the xy plane, which means that the torques involved are parallel to the z axis. Thus, in…

The gravitational force on an extended body is the vector sum of the gravitational forces acting on the individual elements (the atoms) of the body. Instead of considering all those individual elements, we can say that  The gravitational force  on a body effectively acts at a single point, called the center of gravity (cog) of the body. Here…

The translational motion of a body is governed by Newton’s second law in its linear momentum form, given by Eq. 9-27 as If the body is in translational equilibrium—that is, if  is a constant—then d/dt = 0 and we must have The rotational motion of a body is governed by Newton’s second law in its angular momentum form, given by Eq.…

Consider these objects: (1) a app resting on a table, (2) a hockey puck sliding with constant velocity across a frictionless surface, (3) the rotating blades of a ceiling fan, and (4) the wheel of a bicycle that is traveling along a straight path at constant speed. For each of these four objects, 1. The linear…

Many skilled rock climbers suffer from chronic pain that runs along their fingers, and some climbers also display a noticeable bulge along the palm side of an injured finger when they draw the finger in toward the palm. What is the connection between the bulge, the pain, and the physics of climbing? The answer is…