1.3a biomechanical principles

Question 1

what is newtons first law?

Answer 1

-Inertia
a body remains in a state of rest or uniform velocity unless acted upon by an external force

eg pass in rugby - ball continues in a state of rest unless acted upon by an external force (produced by arms, wrists, hands)

Question 2

what is newtons second law?

Answer 2

-acceration
the acceleration of a body is proportional to the force causing it, and the acceleration takes place in the direction in which the force acts

eg golf tee off - the more power the ball is struck with = how quickly it will accelerate and the angle/direction it is struck will determine the direction it will travel

F=MxA

Question 3

what is newtons third law?

Answer 3

-Reaction
for every action there is an equal and opposite reaction

eg sprint start - sprinters feet push force down onto the ground and the ground pushes an equal force back

Question 4

vertical forces

Answer 4

weight (down)

reaction (up)

Question 5

horizontal forces

Answer 5

friction (in direction)

air resistance (opposite direction)

Question 6

what is net force

Answer 6

the sum of all forces acting on a body

Question 7

internal forces

Answer 7

generated by a msk contraction
eg drive out of start blocks

Question 8

external forces

Answer 8

comes from outside the body and acts upon it
eg w, r, f, and ar

Question 9

what are balanced forces

Answer 9

forces equal in size that have no movement

Question 10

what are unbalanced forces

Answer 10

one force is greater than another and there is movement

Question 11

weight

Answer 11

gravitational pull that the earth exerts on a body
-acts down from COM

Question 12

reaction

Answer 12

equal and opposite force exerted y a body in response to the action force placed upon it (N)

Question 13

friction

Answer 13

force that opposes the motion of two surfaces in contact (N)

Question 14

what factors affect friction

Answer 14

-roughness of ground surface
-roughness of contact surface
-temperature
-size of normal reaction

Question 15

air resistance

Answer 15

force that opposes the motion of a body travelling through the air (N)

Question 16

what factors affect air resistance

Answer 16

-velocity
-shape
-frontal cross sectional area
-smoothness of surface

Question 17

what is force

Answer 17

a push or pull that alters the state of motion of a body

Question 18

force calculation

Answer 18

force (N) = mass (kg) x acceleration (m/s2)

Question 19

what is momentum

Answer 19

the quantity of motion possessed by a moving body

Question 20

momentum calaulation

Answer 20

momentum (kgm/s) = mass (kg) x velocity (m/s)

Question 21

what is acceleration

Answer 21

the rate of change in velocity

Question 22

acceleration calculation

Answer 22

acceleration (m/s2) = (final velocity - initital velocity (m/s)) / time taken (s)

Question 23

weight calculation

Answer 23

weight (N) = mass (kg) x acceleration due to gravity (10 ms2)

Question 24

what to do if there is more than one point of contact

Answer 24

eg handstand
reaction force from each hand has to be half of the weight arrow
W=R1+R2

Question 25

centre of mass

Answer 25

the point at which the body is balanced in all direction

Question 26

what affects com

Answer 26

how the body is positioned
eg arms up

if they are holding something
eg bar above head

Question 27

fosbury flop

Answer 27

take off
-com raised with arms and stays outside body by arching

in air
-com under bar while jumper passes over allowing greater height

Question 28

what factors affect stability

Answer 28

centre of mass
-lower com, greater stability

base of support
-greater size bos, greater stability

line of gravity
-central log to bos, greater stability

mass of body
-greater mob, greater inertia and stability