Moments Flashcards
Parallelogram law
states that the sum of the squares of the lengths of the two sides of a parallelogram equals the square of the diagonal connecting the two lengths
AB^2 + BC^2 = AC^2
AB + BC = AC
The Law of Transmissibility
The point of application of a force can be moved along its line of action without changing the external reaction forces on a rigid body
Newtons First Law
a body stay in a state of rest or uniform motion unless acted upon by a force
Newtons Second Law
The rate of change of momentum of a body is proportional to the force acting on it
What can we assume when an object is described as ‘light’
That it’s weight can be ignored
Newtons Third Law
Forces of interaction between bodies are equal in magnitude, share the same line of action, and have opposite senses
Newtons Law of Gravitation
States that every particle attracts every other particle in the universe with a force that is proportional to the product of their masses and inversely proportional to the square of the distance between their centers.
F = (GMm)/(r^2)
When can you consider an object as a practical
When all the force acting on the object act on the same point, the rest of the object can be ignored and the object can be assumed to be a practical
Triangle Law
when two vectors are represented as two sides of the triangle with the order of magnitude and direction, then the third side of the triangle represents the magnitude and direction of the resultant vector
Polygon Rule
(n-2) * 180
define rigid bodies
where the geometrical shape of a body is assumed to be the same in loaded and unloaded cases
define the moment of a couple
2 forces with the same magnitude, parallel lines of action acting in opposing directions
- resultant force = zero
- produces a PURE MOMENT
which direction is the moment rotating if the moment is positive (+)
anti-clockwise
which direction is the moment rotating if the moment is negative (-)
clockwise
How to determine a equivalent force couple system
Determine the moment created from the original point with respect to the new point (using the initial force that was applied there)
