week 6

Question 1

biomechanics

Answer 1

application of mechanical laws to living structures, specially to the locomotor system of the human

Question 2

application of biomechanics analysis

Answer 2

improvement of sport skill techniques
design of sports equipment
prevention of injuries
clinical anysliss of movement pathologies
design of prostheses
design of rehabilitation device
animation for film and video games
ergonomic redesign in the workplace

Question 3

mass, force, and weight

Answer 3

mass: quantity of matter contained in an object
force: mass x acceleration (n)
weight: amount of gravitational force exerted on a body
- weight = mass x acceleration of gravity =mag
acceleration of gravity= 9.81 m/s2
u

Question 4

volume

Answer 4

amount of space a body occupies

Question 5

pressure

Answer 5

force distributed over a given area
F/A

Question 6

compression

Answer 6

pressing or squeezing force directly axially through a body

Question 7

tension

Answer 7

pulling or stretching force directly axially through a body

Question 8

shear

Answer 8

force directed parallel to a surface

Question 9

levers of the human body

Answer 9

a lever is defined as a rigid bar that turns about an axis
bones represent the bars and joints are the axes. contraction of the muscles provides force to move the levers

Question 10

three parts of a lever

Answer 10

force point: the exact point where the effort is applied
restaince point: exact point on which the resistance acts
fulcrum: axis of motion

Question 11

force arm and resistance arm

Answer 11

force arm: perpendicular distance from the fulcrum to the line of action of the force acting on the force point
resistance arm: the perpendicular distance from the fulcrum to the line of action of the resistance acting on the resistance point

Question 12

first class levers

Answer 12

fulcrum between the force point and resistance point

Question 13

second class levers

Answer 13

resistance point between the force point and the fulcrum

Question 14

third class levers

Answer 14

force point at some location between the resistance point and the fulcrum. most common in body, permits muscle to be inserted near the joint and to produce distance and speed of movement although at a sacrifice of force

Question 15

force lever

Answer 15

= force arm > resistance arm
lever favours force output at the sacrifice of speed and distance

Question 16

speed lever

Answer 16

force arm < resistance arm
lever favours speed and range of motion at the sacrifice of force

Question 17

moment arm and torque

Answer 17

perpendicular distance between the forces line of action and the axis of rotation
torque: product of force and moment arm from the forces line of action to the axis of rotation
= force (n) x moment arm (m)

Question 18

centre of gravity

Answer 18

imaginary point in the centre of the body where the weight of the body is balanced

Question 19

why is it useful to determine CG

Answer 19

used to describe the movement of the body through space
importnat for stability
it is an important factor in calculating the amount of work done

Question 21

balance vs stability

Answer 21

balance: ability control equilibrium
stability: firmness of balance

Question 22

stability can be increased by:

Answer 22

increasing body mass- lowers cg
increasing size of the base of support in the direction of the line of action of an external force
increasing friction between the body and the surface
positioning the cg near the edge of the base of support towards the oncoming external force
vertically positioning the cg as low as possible

Question 23

law of inertia

Answer 23

a body will maintain in a state of rest or constant velocity unless acted on by an external force that changes the state
the amount of inertia a body possesses is directly proportional to its mass

Question 24

law of acceleration

Answer 24

force=mass x acceleration

Question 25

law of reaction

Answer 25

when one body exerts a force on a second body, the second body exerts reaction force that is equal in magnitude and opposite in direction on the first body

Question 26

linear momentum

Answer 26

mass x velocity

Question 27

work and power relashonhsips

Answer 27

work= force x distance
power= work per unit of time

Question 28

walking vs running

Answer 28

running there is a period where both feet are off the ground
running there is no period when both feet are in contact with the ground at the same time
stance phase is much smaller portion of the total gait cycle than in walking

Question 29

running speed=

Answer 29

stride length x stride rate
dependant upon leg length and the power of stride
leg speed is mostly dependant on speed of muscle contraction and neuromuscular coordination