Biomechanical movement (P2) Flashcards
What is a scalar quantity?
When measurements are only described in terms of size/magnitude- mass, distance and speed.
What is a vector quantity?
When measurements are described in terms of magnitude and direction- weight, acceleration, displacement, velocity and momentum.
In terms of vectors, what does an arrow show?
The magnitude and direction
What is mass?
The quantity of matter the body possess. Measured in kg
What is weight?
The gravitational force exerted on an object. Measured in Newtons
What is distance?
The path a body takes as it moves from the starting to the finishing position. Measured in metres.
What is displacement?
The shortest route in a straight line between the starting and finishing position.
What is speed?
The rate of change over a distance. Measured in m/s.
What is velocity?
The rate of change of displacement. Measure in metres per second.
What is the formula for speed?
Distance covered (m)/time taken (s)= speed (m/s)
What is the formula for velocity?
Displacement (m)/ time taken (s)=velocity (m/s)
What does a distance-time graph show?
The distance travelled over a period of time.
How do you work out the gradient of a graph?
Changes in y-axis/ changes in x-axis
What do velocity-time graphs and speed-time graphs show?
Indicates the velocity or speed of a performer or object per unit of time.
What is acceleration?
The rate of change of velocity. Measured in m/s^2
What is the formula for acceleration?
Change in velocity (m/s)/ time (s)= acceleration (m/s^2)
What is momentum?
The product of the mass and velocity of an object. Measured in (kgm/s).
What is the formula for momentum?
Mass (kg) x velocity (m/s)= momentum (kgm/s)
What are the two types of force?
Internal and external
What is an internal force?
A force generated from the contraction of the skeletal muscles
What is an external force?
A force generated from outside the body.
What are the vertical forces?
Weight and reaction force
How does weight act as a force to the body? And give an example.
A gravitational force exerted on the body, pulling it towards the centre of the Earth. e.g an aquatic diver will experience the force of gravity pulling them done the pool.
What is a reaction force and give an example?
An equal and opposite reaction force that occurs when two bodies are in contact with each other. e.g when a footballer kicks a football there is an equal and opposite reaction force. Force is exerted against the ball and back on the foot by the ball.
What are the two horizontal forces?
Frictional force and air resistance force
What are the two types of frictional force?
Static and sliding
What is static friction? Give an example
The force exerted on one force by another when there is no motion between the two surfaces. The dry friction between the shoe and the tennis court but with no motion.
What is sliding friction? Give an example
The force exerted on one force by another when there is motion between the two surfaces. e.g when running 100 the push off from the feet is opposed by the friction in the opposite direction.
What factors can friction be affected by?
. The surface characteristics of the two bodies- e.g spikes have generate more friction
. The temperature of the two surfaces in contact. e.g the sweepers in curling increase the temp of the ice
. The mass of the objects that are sliding
What is air resistance?
A force that acts in the opposite direction to the motion of a body travelling through air.
What does amount air resistance depend on?
. The velocity of the moving body
. The cross-sectional area of the moving body
. The shape and the surface characteristics of the moving body
Where is weight drawn from on a free body diagram of forces?
From the centre of mass downwards
Where is reaction force drawn from on a free body diagram of forces?
Starts from where the two bodies are in contact with each other.
Where is friction drawn from on a free body diagram of forces?
Starts from where the two bodies are in contact and is opposite to the direction of any potential slipping.
Where is air resistance drawn from on a free body diagram of forces?
Drawn from the centre of mass opposing the direction of the motion of the body.
What is net force?
The resultant force acting on the body when all other forces have been considered.
What is a balanced net force?
When there are two or more forces acting on the body that are equal in size but opposite in direction.
What is an unbalanced net force?
When a force acting in one direction on a body is larger than a force acting in the opposite direction.
What diagram can show the effects of internal and external forces?
A vector diagram
What are the components of the vector diagram?
vertical force, horizontal force and vertical component.
What is the relationship between the components of the vector diagram?
The relation ship between the amount of vertical force and horizontal force provided by the muscles will lean the vertical component.
What is impulse?
The time it takes a force to be applied to an object or body.
How is impulse calculated?
Impulse (newton seconds) = Force X Time
In terms of Newton’s second law what does an increase of impulse mean?
An increase in the rate of change of momentum. causing a large change of velocity.
What is an example of impulse increasing momentum?
If a tennis player follows through with the racket to increase the amount of time the racket is in contact with the tennis ball. This increases the outgoing momentum of the ball causing the ball to travel faster.
What is an example of impulse decreasing momentum?
At the end of a 60m sprint, they have to stop quickly . To do this, they push their feet hard into the ground to increase the contact time of the foot so they decelerate.
What is net impulse?
A combination of positive and negative impulses
How is impulse represented?
On a force-time graph
What is the net impulse at the start of a 100m sprint?
The net impulse is positive which shows the sprinter is accelerating.
What is the net impulse in the middle of 100m sprint?
Positive and negative impulses are equal (net impulse of zero). This means there is no acceleration or deceleration so the sprinter is running at a constant velocity.
What is the net impulse at the end of the 100m sprint?
The net impulse is negative which shows the sprinter is decelerating.
What is angular motion?
Refers to rotation and involves movement around a fixed point or axis.
What are three examples of angular motion?
. Whole body somersault
. high bar in gymnastics
. arm action in sprinting
What are the three axes that angular motion takes place and give examples?
Transverse axis- somersault
Sagittal axis- cartwheel
Longitudinal axis-Ice skating triple lutz
What is torque?
The rotational consequence of a force
What does the perpendicular distance of the force from the pivotal point mean?
The greater the distance the greater the moment of the force or torque.
How is the moment of the force or torque calculated?
Force (newtons) X perpendicular distance from the fulcrum (metres)
What is Newton’s first law in relation to 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.
What is a practical example of newtons first law of angular motion?
An ice skater performing a triple lutz
What is Newton’s second law in relation to angular motion?
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.
What is Newton’s third law in relation to angular motion?
When a force (torque) is applied by one body to another; the second body will exert an equal and opposite force (torque) on the other body.
What is a radian?
The unit of measurement for angles
What is angular displacement?
The smallest change in angle between the start and finish point of a rotation
What is angular velocity?
The rate of change of angular displacement.
How is angular velocity calculated?
Angular velocity (rad/s)= angular displacement (rad) / time taken (s)
What is angular acceleration?
The rate of change of angular velocity
How is angular acceleration calculated?
Angular acceleration (rad/s^2)= change in angular velocity (rad/s) / time take (s)
What is inertia?
A resistance to change in motion
What is the moment of inertia?
The resistance of a body to angular motion (rotation)
What two things does moment of inertia depend on?
. mass of the body/object
. distribution of mass from the axis of rotation
How does the mass of the body/object impact the moment of inertia?
The greater the mass, the greater the resistance to change and therefore the greater the moment of inertia.
What is an example of the mass of the body/object impacting the moment of inertia?
A ten pin bowling ball is more difficult to roll along the ground than a football but once it starts rolling it is more difficult to stop.
How does the distribution of mass from the axis of rotation impact the moment of inertia?
The closer the mass is to the axis of rotation, the easier it is to turn, because the moment of inertia is low. Increasing the distance of distribution of mass from the axis of rotation will increase the moment of inertia.
What is an example of the distribution of mass from the axis of rotation impacting the moment of inertia?
A somersault in an open position has a higher moment of inertia than in a tucked position. This is because the open position has the mass future away from the axis of rotation.
How does knowledge of the moment of inertia help to improve sprinting technique?
The back leg is the drive leg which is extending, this has a high moment of inertia as more mass is distributed away from the hip joint. The front leg which is recovering has a low moment of inertia which means that he can bring his leg through quicker and start another drive.
What is angular momentum?
The quantity of rotation a body possesses (spin) around an axis.
What does angular momentum depend on?
Moment of inertia and angular velocity
What is the formula for angular momentum?
Moment of inertia X angular velocity
What is the relationship between angular velocity and moment of inertia?
They are inversely proportional
What are some sporting examples of angular momentum?
. Occurs during flight or on ice where there is little friction
. In diving when a performer performes a double somersault, the angular momentum will remain constant until the diver hits the water or changes body position
What does projectile motion refer to?
The movement of either an object or the human body as they travel through the air.
What three factors determine the horizontal displacement of a projectile?
. Angle of release
. Speed of release
. Height of release
What is horizontal displacement?
The shortest distance from the starting point to the finishing point in a line parallel to the ground.
What is the optimum angle of release dependent on?
Release height and landing height
What is the optimum angle of release when the release height and landing height are the same? and give an example
45 degrees
e.g long jumper
What is the optimum angle of release when the release height is below the landing height? and give an example
Above 45 degrees
e.g shooting in basketball
What is the optimum angle of release when the release height is above the landing height? and give an example
Less than 45 degrees
e.g shot put
How does the speed of release affect angular displacement? Give an example
The greater the release velocity of a projectile, the greater the horizontal displacement. In shot put, the rotation in the circle ensures that the shot leaves the hand at maximal velocity and a greater horizontal displacement is achieved.
How does the height of release affect angular displacement?
A greater release height results in a increase in horizontal displacement. The force of gravity is constantly acting on the mass of a shot put.
What factors affect flight paths of different projectiles?
Weight and air resistance
What are the two flight paths that projectiles take?
Parabola and distorted parabola
What projectiles follow a parabolic path? and what is an example
Large weight force and small air resistance force. e.g shot put
What projectiles follow a non-parabolic path?
Low weight force and high air resistance e.g shuttlecock
What is the horizontal vector component of a parabolic flight?
The horizontal motion of an object
What is the vertical vector component of a parabolic flight?
The upward motion of an object
How and why might the vertical vector component change during flight?
Due to weight of the body
How and why might the horizontal vector component change during flight?
It remains the same during flight as air resistance does not affect it.
What is fluid mechanics?
The study of an object or the human body that travels through an liquid or gas.
What is a drag force?
A force that acts in opposition to motion.
What are the two types of drag force?
Surface drag and form drag
What is surface drag?
Relates to the friction between the surface of an object and the fluid environment.
What is form drag?
Relates to the impact of the fluid environment on an object. e.g in the strip stream in cycling where cyclist behind can save up to 30% of their energy
What are the factors that affect drag?
. Velocity of the moving body
. The cross sectional area of the moving body
. Shape and surface characteristics of the moving body
How does the velocity of the moving body affect drag? and how can it be mitigated?
Greater velocity through a liquid, the greater the drag. Can be mitigated through streamlining
How does the cross-sectional area of the moving body affect drag?and how can it be mitigated?
The larger the cross sectional area, the larger the drag. Can be mitigated by e.g crouching when schussing in skiing
How does the shape and surface characteristics of the moving body affect drag? and how can it be mitigated?
The more streamlined, aerodynamic an object is, the less drag there will be. Swim suits, body hair, time trial clothing
What is the Bernoulli principle?
Where air molecules exert less pressure the faster they travel and more pressure when they travel slower.
Using the Bernoulli principle, how does a discuss create the required lift force?
. The optimum angle of attack means that the the air has to travel further on top which means they travel faster as so exert less pressure and the opposite for underneath and the low pressure creates uplift lift force.
What is the optimum angle of release for a discuss to get the best uplift?
25-40 degrees.
Using the Bernoulli principle, how does a formula one car create the required lift force?
Spoiler is angled so that the air travels slower on top creating high pressure and the opposite below so there is a downwards lift force
