Biomechanics Flashcards
define linear motion and give an example for the two types
Linear motion is when a body uniformly moves the same distance, direction during the same time. E.g. running (straight line motion) or swinging a golf club (curvilinear motion)
define angular motion
Angular motion is when a body is in motion around an axis. Can be around a fixed point such as the hips during running or the centre of gravity such as the back spin of a basketball. It is different to linear motion as not all parts travel the same distance and direction within the same time frame
define general motion and describe the general motion of a person riding a bike
General motion is the combination of angular motion of specific parts of the body such as hips or shoulders to cause the body to move linearly (same direction, distance and time).
The biker is using the angular motion of the hips and ankles as well as wheels and pedals of the bike to cause the bike and human body to move linearly. The combination of these two motions causes general motion.
name 3 uses of biomechanics
video analysis computer analysis force platforms streamlining body position refining swimming technique measure muscle force
what is the difference between speed and velocity
speed is the rate that an object moves from one point to another (distance/time)
velocity is the displacement/time and has a direction while speed doesn’t
define acceleration
rate of change of velocity
define mass
the amount of matter that makes up a body
define inertia
a body’s resistance to change of motion
define force
the pushing and pulling action that changes a body’s motion
what is the difference between distance and displacement
distance is the path an object takes from point a - b and displacement is the the distance in a straight line from point a - b
define angular motion and give an example
angular motion is when a body moves around an axis or centre of gravity. This means that different parts of the body will travel at different speeds and distances. The parts of the body furthest away from the axis will travel the furthest and fastest.
an example of this is the angular motion of the femur around the hip joint when running.
explain the four characteristics of sequential motion + draw graph
- use big muscle groups such as legs first
- accelerate each body part sequentially and fluidly to minimise energy “leaking” and optimise momentum transfer
- each body part is stable so that body parts accelerate over a stable base, further minimising energy leakage
- follow through so that the release is at maximum velocity and then decelerate after.
graph: - four crescents
- half way between
- legs + ankles -> hips -> shoulders + trunk -> wrist +arms
- x axis: timing and order
- y axis: level of performance
- title: ideal force + timing summation
what is simultaneous movement
all body parts move simultaneously to maximise explosivity
when would you use sequential motion and simultaneous motion
simultaneous: explosive movements e.g long jump
sequential: used in movements that require power and accuracy e.g three point shot in basketball.
define force and give an example of a contact, non contact, internal and external force
a force is the pushing or pulling force on a body that can change its motion
contact: a player tackling another
non contact: gravity
internal: femur pressing down and tibia pressing up when landing from a jump (joint reaction force)
external: friction
what forces affect a projectile
gravity
air resistance
air pressure
what affect will changing the height, velocity and angle of release on a projectile’s trajectory
height of release: the projectile will have a higher max height and be in the air for longer which allows the horizontal motion more time to travel further
velocity of release: changing the velocity will have the most effect on horizontal displacement. Due to the projectile having a greater velocity gravity will have to overcome more force to push it down therefore the projectile will travel higher
angle of release: the optimum angle of release for horizontal displacement is approximately 45degrees but will have to be adjusted depending on external factors such as wind. the higher the angle of release the higher the max height will be.
explain newtons first law.
law of inertia
a body’s will continue in a state of rest or motion unless acted upon by an external force.
an example of this is a golf ball on a tee. It will stay there forever unless acted upon by an external force such as wind or a club.
explain newtons second law
law of acceleration
when an object is acted upon by a constant force the objects acceleration is proportional to its force and inversely proportional to it’s mass.
when a runner wants to maximise their acceleration they need to have big muscles to increase force production but also be lean because acceleration is inversely proportional to mass.
explain newtons 3rd law
law of action and reaction
every force will have a force with equal magnitude and opposite direction
when running you will push down into the ground and the ground will push back with equal strength but opposite direction which will push you forward.
what is balance and how can you maximise it
a body’s ability to maintain stability
the greater the mass the greater the stability
the greater area the object has with the ground, the greater the stability
keep the centre of gravity over base of support
keep centre of gravity low to the ground
