## What are the forces acting on a rigid body?

The net external force on the rigid body is always equal to the total mass times the translational acceleration (i.e., Newton’s second law holds for the translational motion, even when the net external torque is nonzero, and/or the body rotates).

### How do you find the reaction force of a beam?

Solving for beam reactions

- Draw the beam free body diagram.
- Replace the uniform distributed load (if any) with the equivalent point load.
- Solve ΣMA = 0 (sum of moments about support A).
- Solve ΣMB = 0.
- Using RA and RB found at steps 3 and 4 check if ΣV = 0 (sum of all vertical forces) is satisfied.

#### What are the conditions for rigid body equilibrium?

For a rigid body to be in equilibrium, the net force as well as the net moment about any arbitrary point O must be equal to zero.

**Why does we assumed that a rigid body always in equilibrium?**

When performing static equilibrium calculations for objects, we always start by assuming the objects are rigid bodies. This assumption means that the object does not change shape when forces act on the object. This also means that the object is considered unbreakable. In practice, no real object is unbreakable.

**Is human body a rigid body?**

Rigid Body Dynamics. For analytical convenience, human body segments are considered as rigid bodies. A rigid body is similar to a system of particles in the sense that it is composed of particles. The physical characteristics of a rigid body can be described by its inertial properties: mass and moment of inertia.

## What are the examples of rigid body?

A rigid body is an idealization of a solid body in which deformation is neglected. In other words, the distance between any two given points of a rigid body remains constant in time regardless of external forces exerted on it. Example: A metal rod in an example of rigid body.

### How do you calculate beams?

The formula for the section modulus is beam width times beam depth squared divided by 6. A two 2-by-6 standard beam has actual dimensions of 1.5-by-5.5 inches which would give a section modulus of 1.5 x 5.5 x 5.5 / 6 = 7.6 which is not enough for this example. A 2-by-8 beam would be sufficient.

#### What are the three conditions of equilibrium?

A solid body submitted to three forces whose lines of action are not parallel is in equilibrium if the three following conditions apply :

- The lines of action are coplanar (in the same plane)
- The lines of action are convergent (they cross at the same point)
- The vector sum of these forces is equal to the zero vector.

**What are the 2 conditions of equilibrium?**

Conditions for equilibrium require that the sum of all external forces acting on the body is zero (first condition of equilibrium), and the sum of all external torques from external forces is zero (second condition of equilibrium). These two conditions must be simultaneously satisfied in equilibrium.

**What should be called a rigid body?**

A body is formally regarded as rigid if the distance between any set of two points in it is always constant. In reality no body is perfectly rigid. When equal and opposite forces are applied to a body, it is always deformed slightly.

## Can a rigid body be elastic?

A rigid body can be elastic.