Biomechanics Flashcards
What is linear motion? [4]
- motion in a straight or curved line
- all body parts moving in the same direction
- speed
- and distance
Explain using an example Newton’s 1st law of linear motion. [4]
- law of inertia
- every body continues its state of rest or motion
- unless compelled to change that state by external forces acting upon it
- a football when placed for a penalty will not move until the player puts force on it by kicking it
Define inertia. [1]
the resistance an object has to a change in state or motion
State Newtons 2nd law of linear motion. [4]
Give an example.
- law of acceleration
- the magnitude and direction of the force determines the magnitude and direction of acceleration
- force=mass x acceleration
- If a player kicks a football with large amounts of force to wards the goals the ball will travel fast and towards the goal
State and give an example of Newton’s 3rd law of linear motion. [4]
- law of action/reaction
- for every force there is an equal and opposite reaction
- the harder a player pushes against the ground the further they will go off the ground
- this is ground force reaction
What is the difference between a vector and a scalar quantity. [2]
vector quantities have magnitude and direction
scalar quantities only have magnitude
Define distance. [3]
path the body takes as it moves from starting point to finishing point
scalar
metres
What is the difference between speed and velocity [4]
speed is a scalar quantity
body’s distance moved per unit of time
velocity is a vector quantity
rate and direction of change in position of displacement
what is the equation for
a. speed
b. mass
c. weight
distance/time
volume x density
mass x gravity
Compare mass and weight. [3]
mass is scalar
kg
quantity of matter a body possesses
weight is vector
N
force on a given mass due to gravity
Define angular motion [1]
rotation around a fixed point or axis
Apply Newton’s 2nd law to angular motion [1]
the rate of change pf angular motion of a body is proportional to the torque causing it and the change that takes place in the direction in which the torque acts.
Apply Newton’s 3rd law of motion to angular motion [1]
for every torque there is an equal and opposite torque
What effects an objects moment of inertia during angular motion [4]
the resistance a body has to angular motion
velocity (more velocity=less inertia)
mass of body (bigger mass=bigger inertia)
distribution of mass (closer to the axis of rotation the lower the inertia)
What is a radian [2]
measure of of angles
equal to 57.3 degrees
Explain what is meant by drag. [4]
a resistance force caused by the motion of a body travelling through a fluid (air/water)
acts in the opposite direction to motion
it has a negative affect on velocity
produced from air resistance and friction
What things affect drag? [6]
velocity
the more velocity the more drag
cross sectional area
a larger area will increase drag
shape and surface
the more stream lined and aerodynamic the less drag
Explain how a cyclist might reduce drag [4]
stream line-shape body to move effectively through air
tuck elbows and handle bars in to reduce cross sectional area
bend down to reduce cross sectional area
wear tight clothing to reduce surface drag
What are the two types of drag [4]
surface- friction between the surface of an object and the environment
form- impact of fluid environment on object
Explain a factor that affect drag [2]
velocity- speed increases air resistance
cross sectional area- increases air resistance in more places
shape and surface- smoother surfaces decrease drag
Define lift force [1]
causes a body to move perpendicular to the direction of travel
How will a lift force effect a projectile [2]
- the more lift force a projectile has during flight the longer it will stay in the air
- and the further horizontal distance of travel
Explain Bernoulli’s principle and how it creates an upward force [4]
- air molecules exert less pressure the faster they travel
- and more pressure the slower they travel
- air above a projectile motion is moving faster therefore has a lower pressure than those below the projectile motion
- this creates an upward force
What is the optimum angle of attack for a discus [1]
25-40 degrees
Explain how a downwards lift force can be created [4]
- want the air below the object to be travelling faster
- they will have less air pressure
- creating a downwards force
- Bernoulli’s principle
- 140-155 degrees
Define the term centre of mass [1]
point of balance
point of concentration of mass
Explain how the position of centre of mass will affect performance [3]
position affects stability
if centre of mass is off centre then stability will reduced
if unstable performance will deteriorate
State 4 ways to increase stability [4]
lower the centre of mass
line of gravity to be central
larger base support
mass of performer
Explain one way to increase stability [2]
lower the centre of mass
bend knees, smaller
line of gravity to be central
stand straight
larger base support
both feet on ground, wider
mass of performer
increased inertia
Explain how centre of mass will affect a rugby tackle [5]
wants to remain stable and not fall to the ground
bend knees
keep body straight
have both feet on the ground, spread slightly apart
have more mass as this will increase performers inertia
Give an example of a first class lever in the body. [1]
head/neck flexion and extension
elbow extension
Describe a second class lever include and example [4]
load is in the middle of the fulcrum and the effort planta flexion generate large amounts of force has to lift up whole body weight slow and limited range of movement
Explain where we would see a mechanical advantage [1]
effort arm is longer than load arm
Describe a 3rd class lever with an example [5]
effort in the middle of fulcrum and load hip, knee and elbow flexion has a large range of movement resistance can be moved quickly little force created
State whether the following are 1st,2nd or 3rd class levers
a. elbow flexion
b. elbow extension
c. plantar flexion
d. neck extension
e. knee flexion
a. 3rd
b. 1st
c. 2nd
d. 1st
e. 3rd
Using examples in your answer explain the differences between internal forces and external forces [4]
external forces come from outside of the body
e.g. friction/air resistance/gravity/weight
internal forces are generated by the skeletal muscles
quadriceps contract to extend the knee
Describe an example of a vertical force [3]
weight
the gravitational force exerted by an object
weight = mass x acceleration
Describe friction. [4]
occurs when two or more bodies are in contact with each other
static- no movement
sliding - movement
affected by surface characteristics/ temperature/ mass/ cross sectional area air resistance
Define air resistance and the factors that affect it [3]
a force that acts in the opposite direction to motion
velocity
cross sectional area
shape and surface
Describe the forces acting on a runner accelerating [6]
- weight is pulling runner down towards the ground
- reaction force is when the ground pushes off upwards against the foot
- weight is equal to the reaction force
- air resistance is pushing against player in the opposite direction to the player running
- friction occurs when foot and ground are in contact and acts in direction runner is moving
- friction is greater than air resistance
- it is an unbalanced force
- net force is in direction of motion
What three factors affect horizontal displacement [3]
angle of release
speed of release
height of release
Define projectile motion [1]
the movement of an object or human body as they travel through the air
What are the optimum angles of release in the following situations [4]
release height (RH) = landing height (LH)
RH < LH
RH>LH
shotput
- 45 degrees
- more than 45 degrees
- less than 45 degrees
- 26-38
Explain how the speed of release affects horizontal displacement [1]
the more velocity the greater the horizontal displacement
How does the height of release affect horizontal displacement [1]
the higher the release height the greater the horizontal displacement
What two factors affect the flight path of a projectile [2]
air resistance
mass
What is the difference between a true parabola and distorted parabola [2]
true = matching left and right hand sides
distorted- sides aren’t matching
Explain why a shotput follows a true parabolic path [2]
large mass
less air resistance
Explain why a shuttlecock has a distorted parabolic path [2]
less mass
and greater air resistance
Describe the vectors of a parabolic flight [3]
1 large positive vertical component as it travels upwards
2 reaches max height and there is no vertical components
- larger negative vertical component as it falls before hitting the ground
Define acceleration [2]
rate of change in velocity
m/s2
Runner starts at start line not moving.
Reach speed of 10m/s in 5 seconds.
what is there acceleration [1]
(final-initial velocity)/time
(10-0)/5
2m/s2
Define momentum [2]
product of mass and velocity of an object
kgm/s
A runner weighs 50 kg.
They are running at a speed of 10 m/s.
Calculate their momentum [1]
kgm/s= kg x m/s
50x10
500kgm/s
How can momentum be conserved? [3]
object in flight
both mass and acceleration can be altered
unless external force acts upon it
define net force [1]
the resultant force acting on a body when all other forces have been considered
What is a balanced force [1]
2 or more forces acting on a body that are equal in size
but opposite in direction
What is a vector [2]
have magnitude and direction
when drawing the bigger the arrow the greater the force
Draw a vector of a high jumper [1]
arrow up is longer than horizontal line
Give an example of a balanced force [1]
standing still
air resistance is equal friction
Define impulse [1]
the time it takes for a force to be applied
what is the equation for impulse [1]
force x time
Describe a force time graph for a single footfall of a runner. [6]
graph negative- ground reaction force= foot push off ground
0- foot lifts off the ground
more positive - acceleration
max positive- max speed/steady pace
starts going lower- deacceleration
reaches 0- athlete stops
What a force time graph look like if athlete is slowing down [2]
net impulse is negative
line is more below the graph
What would the
a. x axis
b. y axis
be labelled as on a force time graph [2]
time (s)
force (N)
