Unit 1: Basic Concepts Flashcards
What are the SI units for length, time, mass, temperature and angle?
Length = metres (m) Time = seconds (s) Mass = kilograms (kg) Temp = Kelvin (K) Angle = radians (rad)
Give 2 examples of derived units
Newtons (N)
Pascals (Pa)
What is the multiplication factor for milli?
10(-3)`
How many radians are in 360 degrees?
2π
How are rectangular coordinates labelled?
In terms of x, y & z axis’ (perpendicular to each other)
Name the 3 planes used to describe the human body?
Sagittal plane
Coronal plane
Transverse plane
When are polar coordinates more useful than rectangular coordinates?
Studies of circular objects and when angles and rotations are important
What are the two forms of motion?
Linear & rotatory
What is the deference between vectors & scalars?
Scalars = magnitude only Vector = magnitude + direction
Define velocity
Rate of change of displacement
Define acceleration
Rate of change of velocity
What 2 effects do forces have on an object?
Change position of object in space + deform the shape of object
Name a simple way of measuring forces
Spring balance
What is a newton in terms of SI units?
1 kgms(-2)
When are bodies considered to be at static equilibrium?
When not moving or moving at a constant velocity (i.e. not accelerating)
What is translational equilibrium?
Static equilibrium along straight lines
What is Newton’s third law?
Every action has an equal & opposite reaction
Define mass
Quantity of matter of which a body is composed
Define weight
Force of grvity acting on a body
What is denisty (p)?
Mass per unit volume (m/v)
What is the equation for weight?
W = mg
What is the relationship between centre of mass & centre of gravity?
Centre of mass = centre of gravity if their is gravity (if no gravity there is only a centre of mass)
Define pressure
Force exerted per unit area (P = F/A)
What are the units of pressure?
Pascals
What is the moment (torque) of a force?
The tendency of a force to produce rotation about an axis
What is the equation for moments?
M = Fd
What are the units of moments?
Newton metres (N m)
What is rotational equilibrium?
When th sum of all the external moments acting on a body is equal to zero
Name the component parts of a lever?
Rigid bar
Fulcrum
Effort force
Resistance force
How is mechanical advantage calculated?
MA = Effort arm/Resistance arm
How can it be determined if a system is working at a mechanical advantage or disadvantage?
MA > 1 = mechanical advantage
MA < 1 = mechanical disadvantage
Describe a first class lever
Fulcrum is located between the effort and resistance
Describe a second class lever
Resistance located between the effort and the fulcrum (e.g. wheelbarrow)
Which lever classes always work at a mechanical advantage or disadvantage?
1st class = either
2nd class = always advantage
3rd class = always disadvantage
Describe a third class lever
Effort is located in between resistance and the fulcrum (e.g. tweezers)
What do all the angles in a triangle add up to?
180 degrees
