Statics Exam 1

What is a unit vector

A vector of magnitude one and has no units. It is significant because it is used to represent direction.

What is the difference between absolute and relative vectors

Absolute vectors start at the origin, while relative vectors do not.

What are position vectors

Position vectors have units of length (feet, inches, meters centimeters)

They can indicate where an object is relative to a force, or they can indicate the direction of a force
They are usually names “r” with two subscripts “RAB.” This means the positive vector from (tail) A to (head) B

What are force vectors

Force vectors have units of force (pounds, kilo pounds, Newtons, Kilo newtons)

What is the difference between a vector and a scalar

A vector shows magnitude and direction, while a scalar only shows magnitude.

What are the basis vectors

Vectors i, j, and k are the unit vectors in the x, y, and z directions respectively

What are the components of a unit vector

The sin and cos of its angle are the components of a unit vector. They components are always less than or equal to 1.

Coplanar, concurrent, and colinear key differences

Coplanar: Forces in 2D, they only exist in one plan (x-y)

Concurrent: Forces whose line of action intersect

Colinear: Forces that have the same line of action

What is the equilibrium equation

ΣF = 0

ΣF_X = 0 and ΣF_Y = 0 are scalar equilibrium equations

Tension versus compression

Tension is a pulling force and compression is a pushing force

What is elasticity

When something changes shape due to an applied force but returns to its original shape when that force is removed.

Units for k; US Customary versus SI

US Customary: lb/ft, lb/in, kip/ft

SI: N/m, N/mm, kN/m