Fundamentals of Forces
The US unit used to measure force.
A particle is said to be in this state when the resultant of all forces acting on it is zero.
What is equilibrium?
The perpendicular distance from the line of action of a force to a point is called this.
What is the moment arm?
For a rigid body in equilibrium in 2D, the number of independent equilibrium equations.
What are three?
This structural element in a truss is designed to carry only axial tension or compression.
What is a two-force member?
This principle states that a body at rest will stay at rest unless acted on by an external force.
What is Newton's First Law of Motion?
This vector operation is used to determine the resultant of two or more forces acting on a particle.
What is vector addition?
The moment of force is the product of this and the force magnitude.
What is the distance (moment arm)?
The type of body that does not deform under loading and remains rigid in the analysis.
What is a rigid body?
The method of analysis that involves isolating individual joints to solve for unknown forces.
What is the method of joints?
The physical quantity that requires a force and direction to be described
What is a vector
The equation ∑Fx=0 ∑Fy=0 apply to this kind of particle system.
What is a 2D system in equilibrium?
In two dimensions, moments can be positive or negative depending on this factor.
What is the direction of rotation (clockwise or counterclockwise)?
This type of support allows only rotation but no translation in any direction.
What is a pin support?
In a truss, if m + R = 2j ,the truss is considered this.
What is statically determinate?
This law states that the force between two objects is directly proportional to the product of their masses and inversely proportional to the square of the distance between them.
What is Newton’s Law of Gravitation?
This principle states that the conditions of equilibrium or motion of a rigid body remain unchanged if a force acting on the body is applied anywhere along its line of action.
What is the principle of transmissibility?
If the moment arm is zero, the moment produced by a force is equal to this.
What is zero?
The support type that prevents all movement and rotation.
What is a fixed support?
The method of analysis that involves cutting through the truss to expose internal forces in specific members.
What is the method of sections?
This rule is used to find the resultant of two forces acting at a point by constructing a shape where the two forces represent adjacent sides.
What is the parallelogram law (or parallelogram rule)?
For a particle in equilibrium, the forces acting on it are represented by vectors that do this geometrically.
What is form a closed polygon?
The moment caused by a force tends to produce this type of movement in a rigid body.
What is rotation?
The point at which all the weight of a rigid body can be considered to act.
What is the center of gravity?
The condition where a truss has more members than necessary to maintain its shape and support the load.
What is a statically indeterminate truss