Ch. 4 Moments

Question 1

What is a rigid body?

Answer 1

A system of particles in which the distance between any two particles remains fixed (implies the body has a center of gravity)

Question 2

What are the two ways to calculate the moment of a force?

Answer 2

Scalar version M=Fd

Vector version: M=r x F

Question 3

What is transmissibility?

Answer 3

The ability to slide a force at any point along its line of action and still create the same moment

Question 4

Varignon’s Theorem states:

Answer 4

The moment of a force about a point is equal to the sum of the moments of the force’s components about the point (aka. The principle of moments)

Question 5

What is a couple?

Answer 5

Two parallel forces which are equal in magnitude, opposite direction, and non-collinear (A fancy way of representing/saying a moment)

Question 6

What does the principle of equivalence state?

Answer 6

And equivalent force system produces the same resultant force and moment about any point on a body or in space

Question 7

What does the principle of equivalence produce?

Answer 7

To force/moment systems that are virtually identical in effect or function

Question 8

All systems can be reduced to__?

Answer 8

A single force and single moment

Question 9

What are three systems that automatically reduce to a single force?

Answer 9

1. Concurrent systems
2. Co-planar
3. Parallel

Question 10

What is the litmus test to determine if a system can be reduced to a single force?

Answer 10

System reduces to a single force if the dot product of the resultant moment in the resultant force equals zero.
M(resultant) • F(resultant) = 0

Question 11

What is a wrench?

Answer 11

A force system composed of a single force and a parallel moment