Stuff to memorize

Question 1

3 Characteristics of a force

Answer 1

1) Point of application (the tip or tail of the arrow)

2) Direction (shown by an arrow pointing in the direction that the force would move the body)

3) Magnitude (represented with a number and units)

Question 2

Mechanics is the branch or physical science that deals with ________ and _________ acting on ____________

Answer 2

Energies and forces

acting on Bodies

Question 3

The line of action of a force is an imaginary line drawn to infinity along the arrow. In order to define the line of action we must know the following two characteristics of force

Answer 3

Point of Application

Direction

Question 4

Two systems of units that may be used in structural analysis?

Answer 4

SI Units = The international system of units
Imperial Units = The imperial system of units

Question 5

Unit forces are measured in

Answer 5

Newtons

Question 6

The standard unit of force in the Imperial system is

Answer 6

Pound Force (Lbf)

Question 7

One pound of force is equal to one pound of mass, or:

Answer 7

1 LBF = 1 LB

Question 8

1 LBF = ? N

Answer 8

1 LBF = 4.448N

Question 9

1 Kip = ? LBF

Answer 9

1 Kip = 1000 LBF

Question 10

In structural design we typically refer to the forces applied to a building as

Answer 10

Loads

Question 11

3 types of VARIABLE load

Answer 11

Live (L)
Wind (W)
Snow (S)

Question 12

2 types of PERMANENT loads

Answer 12

Dead Load (D) - ie the weight of the building

Lateral Earth Pressure (H) - ie the horizontal pressure on the foundation of a house

Question 13

1 type of RARE load

Answer 13

Earthquake (E)

Question 14

What is the difference between MASS and WEIGHT

Answer 14

Mass = the amount of matter in a body

Weight = force due to gravity acting on the mass

Question 15

What is the equation to calculate the force of gravity?

Answer 15

F=mg

F= force (N)
m= mass (kg)
g = gravity (9.81N/kg)

Question 16

What are the steps in drawing an FBD

Answer 16

1. Identify the body
2. Draw the free-body
3. Draw the external forces
4. Draw unknown reaction forces an place of support icons
5. Draw dimensions

Question 17

Forces acting on a body are called?

Answer 17

Loads

Question 18

The location of the reaction forces are called the?

Answer 18

Supports

Question 19

The design procedure steps in making a building are

Answer 19

1. Stability -
   Statics is used to calculate the required forces in all members and their connections to the structure remains static under the load
2. Strength -
   Once the forces are known then we use the principles of mechanics of materials to determine if the size and material of the structure will be strong enough to resist the forces
3. Stiffness -
   A final design check is to ensure the size and material of the structure are stiff enough to limit the deformations of the building to within acceptable limits

Question 20

The effect of a force is to move the body in the forces:

Answer 20

Line of action

Question 21

Characteristics of a roller support

Answer 21

Can resist both pushing and pulling forces.

Hold the member to the surface, but allow it to slide along the surface.

Can be positive or negative

(one direction of force)

Question 22

Characteristics of a PIN support

Answer 22

Holds the member in place at that point.

Prevents all translation of the member.

Does allow rotation.

Can be Positive or negative.

(two directions of force)

Question 23

Characteristics of a Cable support

Answer 23

Can only provide tension (pulling) force.

Direction of the force will be in line with the cable.

Always positive

(one direction of force)

Question 24

Characteristics of a Strut

Answer 24

A support with pins at both ends.

Can resist both tension (pulling) and compression (pulling)

(roller gives same type of reaction).

Can be positive or negative

(one direction of force)

Question 25

Characteristics of a Fixed support

Answer 25

Prevents both translation and rotation.

Absolutely necessary if a member has only one support.

To prevent translation, shows horizontal and vertical force

To prevent rotation shows a moment reaction (circular arrow).

All forces can be positive or negative.

Question 26

Characteristics of a Force Couple

Answer 26

a moment reaction (circular arrow)

Two forces with equal magnitude but opposite directions and separated by a distance

moment = force * distance

Total effect of the force of both directions is 0, but because they are separated they cause rotation.