Engineering principles

Question 1

What is the definition of density?

Answer 1

Mass per unit volume

Question 2

What are the units for density?

Answer 2

Kg/m^3

Question 3

What is the definition of relative density?

Answer 3

Ratio of that substance compared to the density of pure water

Question 4

What are the units of relative density?

Answer 4

No units

Question 5

What is the definition of friction?

Answer 5

A force that opposes the relative motion of two surfaces in contact with each other

Question 5

What are the units of friction?

Answer 5

Newtons (N)

Question 6

What is the definition of the coefficient of friction?

Answer 6

A measure of the amount of friction existing between two surfaces

Question 7

What are the factors which affect friction? (3)

Answer 7

1. The nature of the materials in contact
2. The forces pressing the surfaces together, e.g weight
3. The presence or absence of any form of lubricant

Question 8

What are the two types of friction?

Answer 8

Static Friction
Kinetic Friction

Question 9

Briefly describe static friction?

Answer 9

Friction between surface of stationary bodies in contact with each other.
Must be overcome to move either body.

Question 10

Briefly describe kinetic friction?

Answer 10

Friction between surfaces moving relative to each other.
Sliding friction –> Solid surfaces
Viscous friction –> Solid and Liquid or gas

Question 11

How can friction be reduced?

Answer 11

By selecting materials with a low coefficient of friction or by using lubricants or bearings

Question 12

What is the definition of Viscosity?

Answer 12

A measure of resistance of layers of fluid sliding over each other

Question 13

What are the effects of viscosity being lower than the manufacturers rated value?

Answer 13

Power loss will be reduced
Wear rate will increase

Question 14

What are the effects of viscosity being higher than the manufacturers rated value?

Answer 14

Power loss will be increased
Wear rate will be reduced

Question 15

What is the definition of a simple machine?

Answer 15

A device that can change the magnitude or line of action or both magnitude and line of action from a force

Question 16

List 4 examples of simple machines

Answer 16

Pully system
Screw jacks
Gear systems
Levers

Question 17

What is force ratio also known as?

Answer 17

Mechanical Advantage

Question 18

What is movement ratio also known as?

Answer 18

Velocity Ratio

Question 19

What is the definition of a moment?

Answer 19

The product of a force and its perpendicular distance from the pivot point

Question 20

What is a moment also known as?

Answer 20

Torque

Question 21

What is the definition of a couple?

Answer 21

The torque produced by two forces acting 180 apart but in the same direction of rotation

Question 22

In simple beam theory what two conditions are necessary to maintain equilibrium?

Answer 22

Clockwise rotation= Anticlockwise rotation
Upward force= Downward force

Question 23

What is a first order lever?

Answer 23

Fulcrum placed between the effort and the load

Question 24

What is a second order lever?

Answer 24

Load placed between the fulcrum and the effort

Question 25

What is a third order fulcrum?

Answer 25

Effort between the load and the fulcrum