Biomechanics
(HL20533)
Year 2, Semester 1
Contents:
Work, Power, Energy
o (page 2-3)
Work (2)
Power (2)
Energy (3)
Work-Energy Theorem (3)
Linear Kinetics
o (page 4-5)
Impulse-Momentum Relationship (4)
Force-Time Graph (4)
Linear Momentum Conservation (5)
Friction; Inclined Planes (5)
Angular Kinetics
o (page 6-10)
Torques; Static Equilibrium (6)
Levers (6)
Newton’s Laws of Angular Motion; Moment of Inertia; Angular Momentum (7-8)
Angular Power (8)
Energy (9)
Work-Energy Relationship (9)
Centre of Mass (10)
1
, WORK, POWER, ENERGY
Work (S) – Joules
Magnitude of a force applied to an object over a distance, causing the objects
movement in the direction of the force applied.
Energy transferred to object by the force acting over a distance.
Movement must occur, otherwise no mechanical work as no distance.
o Isometric contraction of holding barbell stationary produces no mechanical
work as no motion occurs to move weight over a distance.
1 Joule = 1 Nm
Power (S) - Watts
Mechanical work done per unit of time (rate a force does work).
W = F x ∆s W = F x cos x ∆s
Work = force x displacement Work = force x angle x displacement
Force and displacement are parallel / act in Force and displacement are not parallel / act
the same direction in different directions
More work done Calculate angle to resolve force in the same
Positive work (W>0) direction
Gravity works in same direction as Negative work (W<0)
displacement during skydiving Drag force (air resistance) works in opposite
Concentric contractions: muscular force direction of displacement during skydiving
causing flexion in same direction as muscle Eccentric contractions: musclar force
fibre dispalcement causing extension in opposite direction to
muscle fibre displacement
1 Watt = 1 Joule/sec = 1 Nm/sec
Area under power-time graph indicates the work done.
P=W/t (power = work / time)
P = (F x s) / t P = F x v (power = force x avg
substitute work equation and then simplify
vel)
Energy – Joules
Mechanical energy is the capacity to do mechanical work.
P generated by Neg W = neg P = Pos W = pos P =
neuromuscular- energy absorption energy generation
skeletal system Landing phase of Propulsive phase of
influences ability to CMJ CMJ
generate force
2
(HL20533)
Year 2, Semester 1
Contents:
Work, Power, Energy
o (page 2-3)
Work (2)
Power (2)
Energy (3)
Work-Energy Theorem (3)
Linear Kinetics
o (page 4-5)
Impulse-Momentum Relationship (4)
Force-Time Graph (4)
Linear Momentum Conservation (5)
Friction; Inclined Planes (5)
Angular Kinetics
o (page 6-10)
Torques; Static Equilibrium (6)
Levers (6)
Newton’s Laws of Angular Motion; Moment of Inertia; Angular Momentum (7-8)
Angular Power (8)
Energy (9)
Work-Energy Relationship (9)
Centre of Mass (10)
1
, WORK, POWER, ENERGY
Work (S) – Joules
Magnitude of a force applied to an object over a distance, causing the objects
movement in the direction of the force applied.
Energy transferred to object by the force acting over a distance.
Movement must occur, otherwise no mechanical work as no distance.
o Isometric contraction of holding barbell stationary produces no mechanical
work as no motion occurs to move weight over a distance.
1 Joule = 1 Nm
Power (S) - Watts
Mechanical work done per unit of time (rate a force does work).
W = F x ∆s W = F x cos x ∆s
Work = force x displacement Work = force x angle x displacement
Force and displacement are parallel / act in Force and displacement are not parallel / act
the same direction in different directions
More work done Calculate angle to resolve force in the same
Positive work (W>0) direction
Gravity works in same direction as Negative work (W<0)
displacement during skydiving Drag force (air resistance) works in opposite
Concentric contractions: muscular force direction of displacement during skydiving
causing flexion in same direction as muscle Eccentric contractions: musclar force
fibre dispalcement causing extension in opposite direction to
muscle fibre displacement
1 Watt = 1 Joule/sec = 1 Nm/sec
Area under power-time graph indicates the work done.
P=W/t (power = work / time)
P = (F x s) / t P = F x v (power = force x avg
substitute work equation and then simplify
vel)
Energy – Joules
Mechanical energy is the capacity to do mechanical work.
P generated by Neg W = neg P = Pos W = pos P =
neuromuscular- energy absorption energy generation
skeletal system Landing phase of Propulsive phase of
influences ability to CMJ CMJ
generate force
2
