Section 11: Biomechanical movement Flashcards
What is a scalar quantity?
when measurements are only described in terms of size or magnitude e.g. mass, distance and speed
What is a vector quantity?
when measurements are described in terms of magnitude and direction e.g. weight, displacement, acceleration, velocity, momentum
Definition of mass
mass is the quantity of matter the body possesses
Definition of distance
distance is measured in metres and is the path a body takes as it moves from the starting to the finishing position
Definition of displacement
displacement is measured in metres and is the shortest route in a straight line between the starting and finishing position
Definition of speed
speed is a measurement in metres/seconds of the body’s movement per unit of time with no reference to direction
Definition of velocity
velocity is measured in metres per second and is the rate of change of displacement
Definition of acceleration
acceleration is measured in m/s2 and is the rate of change of velocity
Equation for momentum
momentum (kgm/s)= mass (kg) x velocity (m/s)
What is an internal and external force?
internal force= generated by the skeletal muscles
external force= comes from outside the body
Definition of weight
weight is the gravitational force exerted on an object
Equation for weight
weight = mass (kg) x gravity (9.8)
measured in newtons, N
What is a reaction force?
a reaction force occurs when two bodies are in contact with one another
What is friction?
friction occurs when two or more bodies are in contact with one another
What is air resistance?
air resistance is a force that acts in the opposite direction to the motion of a body travelling through the air
What is impulse? (given as an equation)
impulse = force x time
What is net imupulse?
net impulse is a combination of positive and negative impulses
What is angular motion?
angular motion is movement around a fixed point
What is a torque?
the rotational consequence of a force (a turning force)
What is 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 OR angular displacement over time taken
What is angular acceleration?
the rate of change of angular velocity OR change in angular velocity over time
What is moment of inertia?
resistance of a body to angular motion
What is angular momentum?
the quantity of rotation a body possesses
What is horizontal displacement?
the shortest distance from the starting point to the finishing point in a parallel line to the ground
What 3 factors determine the horizontal displacement of a projectile?
- angle of release
- speed of release
- height of release
What is the optimum angle of release?
angle between the horizontal axis and the direction of the projectile at release
What is the optimum angle of release if the release height and landing height are equal?
45 degrees
What is the optimum angle of release if the release height is below the landing height?
greater than 45 degrees
>45
What is the optimum angle of release if the release height is higher than the landing height?
les than 45 degrees
<45
(for a world class shot-putter it is between 26-38 degrees)
What is a parabola?
a curve with a matching left- and right-hand sides
What is a drag force?
a force that acts in opposition to motion
What are the 2 types of drag force?
- surface drag= friction between the surface of an object and the fluid environment
- form drag= the impact of the fluid environment on an object e.g. streamlining
What is streamlining?
involves shaping the body so it can move as effectively and quickly through a fluid as possible
What is lift force?
Causes a body to move perpendicular to the direction of travel
What is the Bernoulli principle?
where air molecules exert less pressure the faster they travel and more pressure when they travel slower
What is the angle of attack?
the tilt of a projectile relative to air flow
Give an example where a sport limits surface drag
swimmers wear smooth clothing to reduce friction between them and the water
Give an example where a sport reduces form drag
cyclists have streamlined bikes where the handlebars don’t stick out and they occupy a crouched position so air travels over them. swimmers also create a streamlined position as they go through the water
State the factors that reduce and increase drag
- velocity of the moving body- the greater the velocity, the more drag force created, streamlining can reduce this
- cross-sectional area of the moving body- a large area increases drag
- shape and surface characteristics of the moving body- streamline and aerodynamic shape reduces drag
Give an example where reversed Bernoulli’s principle would occur
cyclists maintain a low streamlined position over the handlebars which means the air that travels over the top has to travel a shorter distance than the air underneath so the air above travels at a slower velocity which creates high pressure so a downward lift force is created
What is 1 radian in degrees?
1 radian=57.3 degrees
What 2 forces affect the flight path of projectiles?
- weight(gravity)
- air resistance
What flight path does a shuttle cock follow and why?
- distorted parabola
- lighter mass so air resistance has a greater affect
- unusual shape increases air resistance
What are the vector components of parabolic flight?
horizontal component= the horizontal motion of an object
vertical component= the upward motion of an object
What 3 factors affect friction?
- the surface characteristics of the 2 bodies in contact e.g. spikes help to increase friction in a runner
- the temperature of the 2 surfaces in contact
- the mass of the objects sliding
What are the 2 types of force acting on a performer during linear motion?
- internal
- external
What is an internal force?
applied/generated when our skeletal muscles contract
What is an external force?
comes from outside the body e.g. weight, air resistance, gravity, friction
What are the 2 types of external force?
vertical and horizontal
Which external forces are vertical?
-gravity, weight and reaction force
Which external forces are horizontal?
air resistance, friction
What are the 2 types of friction force?
- static
- sliding
What is static friction force?
static friction force is the force exerted on one surface by another when there is no motion between the 2 surfaces (static friction occurs before an object starts to slide)
What is sliding friction force?
sliding friction occurs when there are 2 bodies in contact with one another that have a tendency to slip/slide over each other
What factors affect air resistance?
- velocity of the moving body: faster the performer moves, the greater the air resistance
- cross-sectional area of the moving body: larger the cross sectional area, greater the air resistance
- shape and surface characteristics of a moving body: streamlined shape and smooth clothing reduce air resistance
How is a weight arrow drawn in a free body diagram?
always drawn down from the centre of pass
How is an air resistance arrow drawn in a free body diagram?
drawn from the centre of mass, opposing the direction of motion of the body
How is a friction arrow drawn in a free body diagram?
starts from where the 2 bodies are in contact with each other and is in the opposite direction to any potential slipping e.g. a runner may slip backwards so the friction arrow is drawn forwards
What is impulse measured in?
newton seconds. it is the time it takes a force to be applied to an object or body
How do you use impulse to increase momentum?
increase the amount of:
- muscular force applied
- time in which a force is applied
How do you use impulse to decrease momentum?
increase the time forces act upon the body or object e.g. 60m indoor sprint, athletes push their feet hard into the ground to increase the contact time of the foot with the ground so they can decelerate quickly
