Ch.1 - Definitions Flashcards
SI units length
m
SI units mass
Kg
SI units time
s
SI units temp
degress Celcius
Derived units force
N
Derived units pressure
Pa=Nm^2
Derived units power
W
1 horsepower = ___ W
746
Non SI units altitude
ft
1 ft = ____ m
0.3048
Non SI units navigational distance
nm
1 nm = ___ m
1,852
Non SI units speed
kts
1 kt = ___ ms^-1
0.514
Acceleration
Change in velocity either speed or direction
For an object to change direction ____ must be imposed
Centripetal force
When speed alone changes there will be
Straight-line acceleration
Mass
Amount of matter in an object
Inertia
The tendency for an object to remain at rest or continue with present velocity (dependent on mass)
Force
Tries to overcome inertia, =ma
Weight
Force produced by mass being attracted to earth gravity, = mass x 9.81, vector as it has magnitude and direction
Momentum
Difficulty stopping a moving object or changing its direction, = mv
Moment
Turning force about a pivot (torque), = F x d
Couple
2 equal but opposite forces that are parallel, moments and couples cause rotation about a pivot, if the forces can be made to change direction as the object turns the rotary motion can be made to continue
Equilibrium
An object in a constant state of rest or velocity, sum of forces is zero
Types of equilibrium
Transitional and rotational
Transitional equilibrium
An object in rest, or moving in a straight line at a constant speed
Rotational equilibrium
Rotating at a constant rate (rpm)
How is a constant rpm maintained
Torque must be balanced by the torque in the opposite direction
Newtons third law
Every action has an opposite and equal reaction
Motion on a curved path
A force must be applied to the centre of the curve (centripetal force)
Centripetal force
= m x v^2/r
