Flashcards
Biomechanical movement
Cards in this deck (95)
- 1define scalar and vector quantitiesscalar: measurements are only described in terms of size or magnitude e.g. mass and speed
Vector: measurements described in magnitude AND direction e.g. acceleration, velocity and momentum - 2How do we calculate weightmass x gravity (9.8) = weight
- 3define mass and weight- physical quantity describing the amount of substance of a body. Scalar quantity as no direction
-weight is a FORCE on a given mass due to gravity. Vector quantity as it has a direction (due to gravity) - 4define distance and displacementdistance - length of path a body follows whilst moving from one position to another. Scalar quantity- just measures size
displacement - length of a STRAIGHT LINE during start and finish points- example of 200 m race (see picture). Vector quantity - also describes direction - 5image to demonstrate the concepts of distance and displacement
- 6define speed and velocitySpeed- measurement of how fast a body moves. Speed is the rate of change of distance. Scalar. Speed= Distance/T
Velocity- how fast a body travels in a certain direction. Rate of change of displacement. Vector quantity. Velocity = displacement/T - 7what units are used for: velocity, distance and time?- velocity and speed= m/s
-distance= m
-time = seconds - 8example of a distance/time graph where the individual is not in motion
- 9example of distance/time graph wherein the person is at a constant speed= e.g. tour de France
- 10Distance/time graph for a person who is accelerating
- 11Distance/time graph for a person who is deceleration
- 12How do we calculate the gradient of a curve?Change in y axis/change in x.
- 13Define acceleration- change in your speed/velocity per unit time (acceleration =speed/time)= m/s^2
- 14Velocity/time graphs for A) constant speed, B) acceleration, C) deceleration
- 15explain this graph (p62)
- 16how do we calculate the acceleration, from the velocityVf= final velocity, Vi= initial velocity, t=time
Vf-Vi/t= acceleration
in m/s^2 - 17Define momentum- product of the mass and velocity of the object
calculated:
mass (Kg) x velocity (m/s)= momentum (Kgm/s) - 18Give an example of how momentum can be conserved- when a performer/object is in flight
- because mass and velocity cannot be altered
- e.g. when throwing a ball, a fast arm action will allow the ball to travel at high velocity, but once in the air, this velocity cannot be changed, unless an external force acts upon it. - 19Describe internal forces- applied when our skeletal muscles contract
e.g. force generated by quadraceps muscles contract concentrically to extend the knee in a jump - 20Describe external forces- comes from outside the body
e.g. friction, air resistance, weight, gravity (often described in terms of weight)
Both forces act on performer in linear motion. Should be able to identify external forces - can be broken down in to vertical and horizontal forces - 21Give two examples of vertical forcesweight
reaction force - 22describe weight as a vertical forcegravitational force- earth exerts on body- pulling it downwards towards centre of earth
-greater mass- greater force pulling body downwards
think about w=mxg - 23describe reaction forces- whatever force acting on performer, will be another force acting equally in opposite direction.
- e.g. footballer kicking a ball- reaction force at point of contact- one between foot and ball and foot and ground. - 24What are the two examples of horizontal forces ?- friction/ force
- air resistance - 25describe friction forces- two type- static and sliding
static: friction asserted by one surface and another- no motion between the surfaces - also called dry friction.
sliding - when there are two bodies in contact with one and other, that may have a tendency to slip or slide over each other - skiing.
Friction acts in opposite to the motion- arrow drawn in opposite direction to motion . - 26name factors that affect friction- equipment such as running spikes help to increase friction as spikes make contact with track
- temperature of the two surfaces- curling example (sweeping generates friction and heat energy)
-mass- of the objects- larger mass= larger friction. - 27Describe air resistance- opposes motion of the body travelling through the air
- depends on the following
1) velocity of the moving body - faster the body moves, greater air resistance
2) cross-sectional area of the moving body - larger the body/area, greater air resistance e.g. why cyclists lean forward over handle bars to avoid large cross sectional area
3) shape and surface characteristics - streamlined shape results in reduced air resistance - cycling helmets, leaning forward, lycra, SHAVE THEIR LEG HAIR ahahahah - 28what is air resistance in water frequently known asdrag - greater density means greater drag
- 29how do we represent forces acting on a performer in linear motion?-free body diagrams
- length, position, direction of arrow important - 30describe how each of the forces described above are drawn on a free body diagram-weight drawn downward, toward the earth
- reaction force- upward, opposing the weight
-friction force= direction of motion
- air resistance - opposes motion of the body - 31image from book- better quality in book p66
- 32describe net force= resultant force acting on a body when the other forces have been considered
- net force often discussed as balanced or unbalanced
- e.g. balanced= standing still- weight and reaction force are equal
e.g. unbalanced force- air resistance higher than weight force when jumping in the air. - 33diagram to represent balanced forces
- 34describe how we can represent internal and external forces on a body- using a vector diagram
-diagram for high jump, wherein the vertical forces are contributing more
- 35Diagram for long jump, wherein the horizontal forces are contributing more.
- 36Describe impulse- is the time it takes for a force to be applied to an object or body
calculated by:
impulse Ns = force (N) x time (s) - 37impulse is equivalent to what?- momentum of a body as a result of a force acting upon it
calculated by
momentum = mass - acceleration. - 38How might we increase the momentum/impulse in sport?- using increasing amounts of muscular force
- e.g. basketball- larger force is generated when jumping for a rebound to catch the ball
also by increasing the amount of time a force is applied- e.g. hammerthrow- 3-4 turn used. - 39How might we decrease impulse/momentum- increase the amount of time a force is acted upon them - e.g. when dismounting from parallel bars, flexion of hips and knees/ankles increases time of the force on the ground (ask teacher- link to equation)
- 40How do we interpret force- time graphs?- area under curve represents impulse
- example of 100m sprint - see photo. Note the small negative impulse at the start which occurs as a result of braking action, followed by positive impulse occurring as the sprinter accelerates
net impulse= sum of impulse - 41diagram to demonstrate sprinter at start of a race
- 42diagram of sprinter in middle of the race- note the equal positive and negative impulse that occurs when sprinter applies force to track and then off the track
- 43diagram of sprinter finishing race- note the net negative impulse - demonstrates deceleration
- 44define angular motion- involves movement around fixed point, or axis
can involve a hole body in somersault , or when throwing a discus
-occurs when force applied outside centre of mass - 45Off centre forces are also known as?eccentric forces
- 46angular motion can occur in three axes. What are these?- transverse axis
-sagittal axis
- longitudinal - 47transverse axis - somersault
- 48Sagittal axis- cartwheel
- 49Longitudinal axis- multiple spins e.g. ice skating
- 50define a torque/moment- turning force - causes a object to turn about its axis of rotation
moment/torque= force x perpendicular distance from the fulcrum - 51outline Newton's first law of angular motion.- a rotating body will continue to turn about its axis of rotation with constant angular momentum, unless an external rotational force (torque) is exerted upon it.
- 52outline Newton's second law- The rate of change of angular momentum of a body is proportional to the force (torque) causing it and the change that takes place in the direction in which the force (torque) acts.
- the greater the torque applied- greater acceleration will be - 53Outline Newton's third law- When a torque is applied by one body to another, the second body Will exert an equal and opposite torque on the other body
- e.g. Goalkeeper tipping ball over the cross bar- throw arms up in air whilst legs go back - 54Define angular displacement- smallest change in angle between starting and finishing point
- measured in degrees and radians (1 radian= 57.3 degrees). - 55define the angular velocity- refers to the rotational speed of an object and the axis about which the object is rotating
vector quantity
equation :
angular velocity = angular displacement/time
angular displacement in radians, angular velocity in radians/second. - 56Define angular accelerationrate of change of angular velocity
angular acceleration (radians/s^2)= change in angular velocity (radians/second)/time taken - 57define and describe moment of inertia- inertia is resistance to change in motion
-moment of inertia is resistance of a body to angular motion (rotation).
depends on the MASS of the body and MASS around the axis - 58describe the importance of mass of the body/object in terms of moment of inertia- greater the mass, greater resistance to change- therefore greater moment of inertia
e.g. ten pin bowling ball harder to start moving that a football, but more difficult to stop. - 59describe the importance of the distribution of mass of from the axis of rotation in terms of moment of inertia- closer mass is to the axis of rotation, easier it is to turn- moment of inertia is low.
- increasing distance from axis of rotation will increase moment of inertia
e.g. tucked somersault has lower
moment of inertia compared to open somersault- due to reduced distance from axis of rotation - 60how might sprinters use the moment of inertia to their advantage?- when leg is extended (back leg), moment of inertia higher, as distance further from the axis of rotation (hip joint)
- when leg is raised, closer to the axis of rotation, which lowers moment of inertia. - 61Define and describe angular momentum- quantity of rotation a body possesses
-more simply- spin.
Equation
angular momentum = moment of inertia x angular velocity
these are inversely proportional. - 62describe the conservation of angular momentum- angular momentum is conserved
- stays constant unless external torque act upon it
- in sport, occurs during flight or on ice and snow where there is reduced friction
- e.g. diver during 10m event has constant angular momentum
(look at equation p78) - 63describe projectile motion- refers to the movement of either an object or human body as they travel through the air \
e.g. any ball that is kicked/thrown. - 64list factors affecting horizontal displacement of a projectile1. angle of release
2. speed of release
3. height of release - 65Describe how the angle of release of a body or object influences displacement- important in object distance
- optimal angle dependent on please height and landing height
- When both release height and landing height are equal, the optimal angle is 45 degrees (ignoring other factors such as air resistance)
-if release height is BELOW the landing height- optimal angle needs to be GREATER than 45 degrees- e.g. basketball
-if release height is GREATER than landing height, then release angle needs to be LESS THAN 45 degrees. Example of javelin/shotput - 66—
- 67what does research show regarding the optimum angle of release for a world class shot putter?- 26-38 degrees
- 68Describe how the speed of release of a body or object influences displacement- greater release velocity of projectile, greater the horizontal displacement travelled
-shotput example - 69Describe how the height of release of a body or object influences displacement- greater height of release also increases horizontal displacement
-force of gravity constantly acting on gravity - therefore the shot-putter should try to release the shot at the heigh point possible to gain maximal horizontal displacement - 70name factors affecting flight paths of different projectiles- weight of the object
-air resistance
two factors influence whether flight path is truly parabolic or distorted parabola - 71describe a parabolauniform curve- symmetric at highest point
- 72What is the typical flight path for projectiles with large weight ?- low air resistance force
-therefore follow a true parabolic flight path
good example- shot-put - 73example parabola of a shotput in flight.
- 74What is the typical flight path for projectiles with lower weight ?- effect of air resistant results in a flight path that looks like a distorted parabola
-e.g. shuttlecock
- 75describe how we can apply vectors to parabolic flight- need to consider both vertical and horizontal components
- the resultant flight path is the resultant of these components
-Note- horizontal component remains the same throughout flight
-air resistance is negligible - 76diagram to explain above card
- 77describe fluid mechanicsstudy of object or body that travels through any liquid or gas
e.g. swimmers
slowed by friction/drag - 78describe dynamic fluid force- concerned with movement of liquid and gases
- is a branch of fluid mechanics and how forces affect them
-drag and lift are dynamic fluid forces - have an effect on a variety of sports- cycling, sprinting, swimming - 79Describe drag forcesslows object down
- resistant force caused by the motion of a body travelling through a fluid
- drag force acts in opposition to direction of motion- negative effect on VELOCITY
-produced from air resistance and friction - 80diagram to describe thrust - most athletes do not have engines (so don't put this in exam)
- 81name the two different types of drag-surface drag
- form drag - 82describe surface drag- relates to friction between the surface of an object and the fluid environment - AKA skin drag.
e.g. swimmers wear specialised swim wear, shave off body hair from arms and torso to reduce surface drag - 83describe form drag- relates to impact of the fluid environment on the object AKA shape drag
these forces affecting the leadings edge of the object increase form lag, and the forces affecting the trailing edge reduce form lag
-relates to streamlining.
large form drag offers less turbulent air for anything that is following
e.g. in cycling drafting- slip-streaming - 84name factors that reduce and increase drag-velocity of moving body
- cross sectional area of moving body
-shape/surface characteristics of moving body - 85How does velocity of a moving body influence drag?- greater velocity of body through fluid- greater the drag force.
-e.g. racing car, sprinter, cyclists will experience greater air resistance and therefore increases drag.
-Therefore, important to decrease drag through streamlining in these sports - 86How does the cross sectional area of a moving body influence drag?- large cross sectional area increases drag
- some sports, reducing drag is critical. e.g. crouching over handle bars in cycling - reducing cross sectional area and therefore drag
- 87ya boiye boi
- 88How does the shape and surface characteristics affect the drag of a moving body?- More streamlined, aerodynamic shape reduces drag
- e.g. speed skier
speed skater- streamlined helmet- looks stoopid
- elite swimmers shave off their hair - 89Describe the Bernoulli principle-when discus is thrown - experiences upward lift force during flight
- lift force enables discus to stay in flight for longer- increases horizontal distance
- lift achieved when different air pressures act on an object
-air that travels faster has a lower pressure than air that travels slower= Bernoulli principle - 90What is the angle of attack?- changes the flow of air over the discus - so the air that travels over the discus has to travel a longer distance than beneath the discus
-creates low pressure.
-this creates list. - 91What will happen if the angle of attack is too great?- list is reduced and drag increases- discus stalls
- 92What is the optimal angle of attack for discus?- 25-40 = best lift
- 93Bernoulli principle diagram
- 94Give an example of when lift is not upward (still Bernoulli effect)racing cars- car pushed down to ground to create a greater frictional force - spoiler angled so that the car is pushed downward in to the ground to create a greater frictional force on the track- this is still the Bernoulli principle
THINK OF OTHER EXAMPLES - p88 for help - 95—
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- A level Physical Education (PE) Flashcards on Biomechanical movement , created by William Holcroft on 02/01/2019.
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