Biomechanics

Question 1

forces

Answer 1

internal: skeletal muscle contract
external: outside
vertical: weight (gravitational force), reaction force
horizontal:
frictional: static (between surfaces before slide), sliding (moving)
affected by: surface characteristics, temperature, mass,
air resistance: dependent on velocity, cross sectional area, shape and surface c

Question 2

net force

Answer 2

resultant force
balanced = 0

Question 3

force-time graph

Answer 3

N.I = +ve = accel
0=constant v
-ve=decel

NI = combination of +ve and -ve impulses

Question 4

impulse

Answer 4

I=FxT
used to add speed or slow down
increase momentum = increase muscular force, increase amount of time force applied (e.g 3-4 turns in a hammer)
decrease m = increase time force acts upon e.g landing

Question 5

mechanical advantage

Answer 5

F>R
large load over less distance with less force
less ROM = less speed and d
2: larger force has to lift whole body
1&3: larger ROM and resistance can be quickly removed

Question 6

mechanical disadvantage

Answer 6

R>F
not heavy
faster
increase ROM
2: slow, limited ROM
1&3: cannot apply much force to move a object

Question 7

examples of levers

Answer 7

1: throw-in
2: jump
3:

Question 8

angular momentum

Answer 8

quantity of rotation a body possesse
AM= MOI x AV where moi and av are inversely proportionate = 1 increase other decrease
conserved quantity = stays constant unless external F/T acts (N1)

Question 9

vector diagram

Answer 9

represents internal and external forces
x:height y:distance

Question 10

moent of inertia

Answer 10

resistance of a body to AM
increase mass = increase resistance to change therefore increase MOI
closer mass to axis of rotation = easier to turn as MOI is low

Question 11

angular motion

Answer 11

movement around a fixed point of axis
occurs when f is applied outside COM
–> eccentric F: off-centre force
occurs as a result of torque (rotational consequence of a f/ turning f)
increase F = increase T
f away from axis = increase T
moment of F/T = F x perpendicular d from fulcrum

Question 12

applying torque to N

Answer 12

1) continue to turn about axis of rotation with constant AM unless external rot f (T) is applied
2) rate of change of AM is proportionate to force/ T causing it and take place in direction of F/T
3)F/T applies to 1 body, 2nd body will exert equal and opposite F/T

Question 13

angular quantities

Answer 13

A. displacement: smallest change in angle between start and finish point of rotation
A. velocity: rate of change of AD
A. acceleration: rate of change of AV

Question 14

displacement

Answer 14

shortest route in straight line between starting and finishing point

Question 15

definitions

Answer 15

speed: rate of change of distance
velocity: rate of change of displacement
acc: rate of change of velocity
momentum: product of mass and velocity of an object

Question 16

factord affecting stability

Answer 16

• height of COM: lower = decrease
• position of line of gravity: central over base of support = increase
• area of support base: increase = increase
• mass of performer: increase = increase because of increased inertia

Question 17

N1

Answer 17

law of inertia
an object will continue in a state or rest or motion in a straight line unless compelled to change that state by external forces exerted upon it
bigger mass = increase inertia

Question 18

N2

Answer 18

law of acceleration
magnitude and direction of force determines magnitude and direction of acceleration
rate of momentum is proportionate for force causing it
f = ma
is mass is constant, a = size of force causing it

Question 19

N3

Answer 19

law of action/ reaction
to every action/ force, there is an equal opposite reaction force
GRF: force exerted on ground by body in contact with it
contact force decrease, opposite ground reaction force increase

Question 20

weight

Answer 20

mass x g