Engineering Principles

Question 1

What is the definition of density?

Answer 1

The density of a substance is defined as its mass per unit volume.

Units are Kg/m^3

Question 2

What is the definition relative density?

Answer 2

Relative density of a substance is the ratio of the the density of that substance compared to the pure density of water.

Question 3

What is the definition friction?

Answer 3

Friction is the force which opposes the relative sliding motion of two surfaces in contact with each other.

It is measured in Newtons.

Question 4

What are the two kinds of friction?

Answer 4

• Static friction
  -Kinetic friction

Question 5

What is static friction?

Answer 5

This is friction between surfaces of two stationary bodies on contact with one another.

Question 6

What is kinetic friction? what are the two types of kinetic friction?

Answer 6

This is friction between surfaces moving relative to one another.

sliding- between two solid surfaces
viscous- between a solid and fluid

Question 7

What is the coefficient of friction?

Answer 7

The measure of the amount of friction between two surfaces.

Question 8

What factors can effect friction?

Answer 8

1. The nature of the materials in contact
2. The perpendicular forces between the 2 surfaces
3. The presence/absence of any form of lubricant

Question 9

What is meant by viscosity?

Answer 9

Viscosity is a measure of a fluids resistance to flow.

Question 10

What are the consequences of high viscosity?

Answer 10

High viscosity = thick
Increased power losses but reduced wear rate to machinery.

Question 11

What are the consequences of low viscosity?

Answer 11

Low viscosity = thin
Reduced power losses but increased wear rate to machinary.

Question 12

Define a simple machine?

Answer 12

A simple machine is a device that is used to change the size/direction of the line of action of an applied force.

Question 13

What are the four examples of simple machines?

Answer 13

• Pulley system
• Screw jack
• Geared system
  -Lever

Question 14

Define mechanical advantage?

Answer 14

This is the ratio of LOAD to EFFORT required to move it.

Question 15

What is mechanical Advantage also known as?

Answer 15

force ratio

Question 16

Define velocity ratio?

Answer 16

This is the ratio of ‘distance moved by EFFORT’ to @Distance moved by LOAD’

Question 17

What is velocity ratio known as?

Answer 17

movement ratio

Question 18

Briefly explain how a screw jack works?

Answer 18

The screw of the jack is fixed in the body of the jack. As the table is rotated by the bar, it raises or lowers a load placed on the table.

Question 19

What is the formula to calculate velocity ratio of a geared system?

Answer 19

Velocity ratio= No of teeth on follower/no of teeth on driver

Question 20

Define a moment of force

Answer 20

A moment is the turning effect of a force.
Measured in Newton meters.

Question 21

Define a couple

Answer 21

A couple is a pair of forces, equal, oppositely directed and displaced by perpendicular distance.

Question 22

What are the two conditions for static equilibrium?

Answer 22

Forces up = Forces down

CWM =ACWM

Question 23

When multiplying two or more numbers with the same base, what do you do with the indices?

Answer 23

Add them

Question 24

When dividing two or more numbers with the same base, what do you do with the indices?

Answer 24

Subtract them

Question 25

What is a number raised to the power of zero equal to?

Answer 25

1

Question 26

What do you do when a number is raised to a negative power?

Answer 26

You turn it into a fraction

e.g. 2^-1 = 1/2

Question 27

How do you solve a power raised to another power?

Answer 27

You multiply them.
e.g. (2^5)^2 =2^2x5 = 2^10

Question 28

What do you do when a number is raised to a fraction?

Answer 28

You route it, the denominator is what it is routed by, and the numeration becomes the power.
e.g. 16^3/4 = 4√ 16^3

Question 29

List the common prefixes

Answer 29

G - giga- x10^9
M- Mega-x10^6
k-Kilo-x10^3
m-mili- 10^-3
µ-micro-10^-6
n-nano- 10^-9
p-pico- 10^-12

Question 30

What is the equation of a straight line? What do each parts mean?

Answer 30

y=mx+c
m = gradient
c= y-intercept