Biomech Unit 1 Flashcards
What are the base SI units?
Length (m) Time (s) Mass (kg) Temp (k) Angle (rad)
What are non base SI units called? give an example
Derived units
Newton (kgms-2)
What coordinate planes correspond with the coronal, saggital and transverse planes?
Coronal: xy (splits front + back)
Saggital: yz (splits side-side - like a saddle)
Transverse: xz (horizontal)
What are polar coordinates?
Angle and length from a fixed point?
What is the difference between the centre of mass and centre of gravity?
Centre of mass: depends upon how the mass is distributed in a body (Each segment has its own centre of mass)
Centre of gravity: only exists in a gravitational field, same point as centre of mass
What are the units of torque/moments?
Newton metres
What are the fulcrum, effort arm + resistance arm?
Fulcrum = centre of rotation
Effort arm = the arm the effort force is applied to
Resistance arm = the arm the resistance force is applied to
How is mechanical advantage calculated and what does it mean?
MA = effort arm/ resistance arm
MA> 1 = mech adv, MA < 1 = mech disadv
(if effort arm greater than resistance arm = mech adv)
Describe the 3 types of lever
First class: fulcrum is in the centre
Second class: the fulcrum is at one end with the resistance/load closest and the effort further away (mech adv)
Third class: the fulcrum is at one end with the effort load closest and the resistance/load further away (mech disadv - lever arm is shorter, almost all muscles are 3rd class)
What type of lever are most muscles in the human body?
Third class
What are the differences between rectangular and polar coordinate systems?
Rectangular: 3 dimensional
Polar: 2D, angle from a fixed point
What are the 2 effects a force can have on a body?
Change in motion (rigid body mech)
Deformation (deformable body mech)
What is the condition for static or rotational equilibrium?
Must be at rest or moving with constant linear/rotary velocity
What is a plane?
A flat 2D surface that has no thickness
