Aero Science

Question 1

SI UNITS
- length
- mass
- time

Answer 1

• m (meters)
• kg (kilograms)
• s (seconds)

Question 2

Units - temp

Answer 2

C (Celsius) or K (Kelvin)
- 0C = 273K
- a change of 1C = a change of 1K

Question 3

Derived units - Force

Answer 3

Measured in Newtons (N), where 1N is the force required to accelerate 1kg of mass at 1ms^-2

Question 4

Derived units - pressure

Answer 4

Measured in pascals (Pa), where 1Pa = 1N per m^2

Question 5

Non SI units - horse power

Answer 5

1HP = 746 W

Question 6

Non SI Units - speed

Answer 6

Measured in kts, where 1kt =
- 0.514m/s
- 1.85km/h

Question 7

Non SI Units - navigational distance

Answer 7

Nautical miles (nm), where 1nm = 1852m

Question 8

Non SI Units - altitude

Answer 8

Feet (ft), where 1ft = 0.3048m

Question 9

Derived units - Power

Answer 9

Measured in watts (W), watts are equivalent to Nm/s, Power = W/t

Question 10

Scalar vs vector quantities

Answer 10

• scalar only has magnitude/size e.g temp
• vector has both magnitude + direction

Question 11

How are vector quantities represented

Answer 11

By a vector arrow with its length representing magnitude and the arrow head representing direction

Question 12

Vector addition/subtraction with multiple vectors acting in the same direction

Answer 12

Simply combine head to tail to produce resultant

Question 13

Combining vectors acting in different directions

Answer 13

Drawing them with the tail of one vector connected to the to the head of the other

The resultant is the vector that can be drawn from the tail of the first to the head of the last

Question 14

Combining vectors originating from the same point

Answer 14

Resultant can be found by drawing a parallelogram, the resultant is formed by the diagonal that goes from the start point of both vectors to the interception point of the parallelogram

Question 15

Resolving single vectors

Answer 15

Any single vector can be resolved into 2 components that are at right angles to each other (note: components can be drawn in any direction as long as the vector is within the right angle)

Question 16

Trig functions

Answer 16

Describe the relationship between vectors and their components, they represent the ratios between lengths of sides of a right angle triangle
- sine (sin)
- cosine (cos)
- tangent (tan)

Question 17

Trig function equations

Answer 17

• sin🌀 = O/H
• cos🌀 = A/H
• tan🌀 = O/A

Question 18

Trig functions small angle

Answer 18

If less than 15• , the cos of the angle is very close to 1 so for practical purposes H=A

Question 19

Describing motion

Answer 19

• speed = distance traveled/time taken (is a scalar quantity)
• velocity = distance travelled in a given direction/time taken (is a vector quantity)
• acceleration occurs when there’s a change of velocity (can be direction and/or speed change)

Question 20

Newtowns first law

Answer 20

Every object continues in its state of rest or uniform motion in a straight line unless acted upon by an external force

Question 21

Inertia

Answer 21

Is the tendency of an object to continue moving at a certain velocity (or to remain at rest with 0 velocity)

Question 22

What does inertia depend on

Answer 22

Solely on mass, so the larger the mass the larger the force required to overcome its inertia

Question 23

Mass

Answer 23

The amount of matter in an object

Question 24

Force

Answer 24

Tends to move the object out of its state of rest or uniform motion in a straight line, a net force must be available to cause acceleration

Question 25

Newton’s second law

Answer 25

The external force acting on a body is proportional to the products of its mass and acceleration production by the force (F = ma)

Question 26

Hectopascal

Answer 26

Used to measure atmospheric pressure, where 1hPa = 100Pa

Question 27

Weight

Answer 27

Is the force produced when a mass is acted upon by gravitational attraction, measured in N (whereas mass is measured in kg)

Question 28

Weight equation

Answer 28

W = m x g

g = is the acceleration due to gravity (and for masses on/near the earths surface g = 9.81ms^-2)

Question 29

‘g’

Answer 29

1’g’ = normal acceleration of gravity
2’g’ = means acceleration that is x2 gravity and a person subjected to 2’g’ will feel twice as heavy as their normal weight

Question 30

Momentum

Answer 30

= mass x velocity

It refers to the difficulty of stopping a moving object or changing its direction of travel

Question 31

Newtons third law

Answer 31

For every action there is a opposite and equal reaction

Question 32

Work

Answer 32

Work is done when a force moves an object through a distance (W=Fxd), its measured in Nm or J (1J = a force of 1N moves an object 1m)

Question 33

Power

Answer 33

Is the rate at which work is done

Question 34

Energy

Answer 34

Is the capacity to do work (measured in J) it comes in various forms such as
- KE = 1/2mv^2 (energy due to motion)
- potential energy (is the energy of position e.g gravitational potential energy)

Question 35

Moment

Answer 35

It is a turning force about a pivot/turning point (turning force is also known as torque or leverage)
- m = Fxd (where distance is arm length)
- measured in Nm (or kg-mm)

Question 36

Couple

Answer 36

Consists of 2 equal but opposite parallel forces, when the forces of a couple act around a midway point torque is produced

Question 37

CG

Answer 37

Centre of gravity (or centre of mass) - the weight of an object acts through its CG, if an object is suspended from its CG or point directly above, it will balance and not rotate, however, if the suspension point/pivot point is displaced horizontally from the CG a moment will exist and the object will not balance

Question 38

Translational equilibrium

Answer 38

An object in a state of rest or constant velocity is said to be in equiibrium (as the sum of all forces acting upon it is 0 so no net force will exist to cause acceleration

Question 39

Rotational equilibrium

Answer 39

Occurs when object is either rotating a constant velocity or not rotating at all, theres no angular acceleration and the sum of all moments acting on the object is 0 (so if torque exists in one direction it is balanced by toque in the opposite direction)