Motion :) Flashcards
horizontal displacement
shortest distance from the starting point to the finishing point - the way the crow flies
three factors affecting it:
- angle of release
- speed of release
- height of release
angle of release
optimum angle dependent upon release and landing height
release + landing height EQUAL- 45 degrees
release height BELOW landing- greater than 45 degrees
release height ABOVE landing- less than 45 degrees
speed of release
greater the speed/velocity the greater the horizontal displacement
speed of shift (force) also affects horizontal displacement, like a shotput using speed and power from spin before to go further
height of release
a greater release height results in increased horizontal displacement
gravity constantly working to pull it down so the higher it starts off the longer it will take to reach the ground
true parabola
uniform curve that is symmetrical at its highest point
projectiles with large weight force (shotput) have SMALL air resistance and will follow a true parabolic flight
distorted parabola
non uniform curve - squished at the end
projectiles with lighter mass (shuttlecock) will increase in air resistance working against it halting the flight leading to a non-parabolic flight
vertical component
upward motion of an object - affected by gravity
horizontal component
horizontal motion of an object - remains constant
drag force
acts opposite to the direction of motion and negatively effects velocity
produced from air resistance and friction
surface drag
friction between the surface of an object and the fluid environment
-swimmers shave or wear tight smooth clothing to reduce surface drag
form drag/shape drag
impact of the fluid environment on the object
streamlining is key
streamlining
involves shaping body so it can move quickly and effectively through a fluid
reducing the frontal cross-sectional surface area also makes them more streamlined
-swimmers create thinnest and straightest shape to move quicker
slipstreaming
large form drag offers less turbulent air in pocket behind the first object
-wind hits first cyclist and goes round the sides so second cyclist can save 30% energy by going 15-30 cm behind
factors increasing and reducing drag
- velocity of moving object: the greater the velocity, the greater the drag force
- faster sports like sprinting, race car driving need to reduce drag more - cross-sectional area: larger c-s area increases drag
- cyclists and skiers crouch down to reduce area and drag - shape and surface characteristics: streamlined, aerodynamic shape key
- drag resistant clothes may help. skiers helmet goes to shoulders
bernoulli’s principle
where air molecules exert less pressure the faster they travel and more pressure when they travel slower
lift force
causes the body to move perpendicular to the direction of travel
allows object to stay in the air longer which increases horizontal distance
angle of attack
the tilt of the projectile relative to the air flow
if too great, then too much drag will result
-ideal is between 25 and 40 degrees
producing lift force on a discus
angle of attack changes the flow of air around the discus
- air above the discuss has to travel further than air below
- air above travels at a faster speed
- meaning air above has a lower pressure than air below
- lower pressure above creates upward lift force allowing discus in the air longer
- increased horizontal displacement
producing greater frictional force - F1
formula 1 car has a spoiler angled to direct the lift force downward
- air traveling over the top has a shorter distance as the spoiler creates a longer distance underneath the car
- air above the car travels at a slower velocity and higher pressure
- creates a downwards lift force and greater frictional force
- tyres maintain firm grip when traveling round the corners fast
scalar quantity
measurements described only in size/magnitude:
-mass, distance, speed-
vector quantity
measurements described in terms of size and direction
-weight, acceleration, displacement, velocity and momentum
mass
quality of matter a body possesses (kg)
distance
path a body takes as it moves from the starting to finishing point (m)
speed
rate at which a body moves per unit of time (m/s)
speed = distance ÷ time
weight
gravitational force exerted on an object (N)
weight = mass x gravitational field strength
displacement
shortest route in a straight line from point a to b (m)
velocity
rate of change of displacement (m/s)
velocity = displacement ÷ time taken
acceleration
rate of change of velocity (m/s2)
acceleration = change in velocity ÷ time
momentum
product of the mass and velocity of an object (kgm/s)
momentum = mass x velocity
constant speed
-middle of long distance run-
performer is stationary
-netball player taking a shot-
accelerating is occurring
-first 20m of 100m sprint-
deceleration is occurring
-once performer has crossed the finish line-
forces acting upon during linear motion
internal force: skeletal muscles contracting
external force: outside the body such as gravity, air resistance + weight
weight
weight is a gravitational force that the earth exerts on the body
-vertical force downwards towards core of the earth-
greater the mass the greater the weight force
friction
friction occurs when two or more bodies are in contact with one another - static and sliding
affected by:
- surface characteristics of objects - running spikes
- temperature of surfaces - ice being swept in curling
- mass of the objects - larger mass = greater friction
air resistance
opposes the motion of a body and depends on:
- velocity - faster velocity = increased air resistance
- cross sectional area - larger cs area = increases air resistance
- shape and surface - streamlined shape = decreased air resistance
horizontal forces
air resistance
friction
vertical forces
weight/gravity
impulse
time it takes a force to be applied to an object
force x time
done by increasing amount of:
- muscular force applied
- time in which force is applied
torque
a rotational force
angular motion
movement around a fixed point or axis
occurs when a force is applied outside the centre of mass
eccentric force
force applied off-centre to create angular motion
newtons first law - angular m
a rotating body will continue in its state of angular motion unless an external force is exerted upon it
newtons second law - angular m
rate of change of angular motion is proportional to the force (torque) causing it
newtons third law - angular m
when a force (torque) is applied by one body, the second body will exert an equal and opposite force on the other body
angular displacement
the smallest change in angle between the starting and finishing points
angular veloicty
the rotational speed of an object and the axis it is rotating on
angular acceleration
the rate of change of angular velocity over time
moment of inertia
resistance of a body to angular motion (rotation)
depends on the mass and its distribution of mass around the axis
angular motion and inertia relationship
inversely proportional
if one increases the other decreases
decreasing moment of inertia
decrease the distance of the distribution of mass from the axis of rotation e.g. tucked somersault
producing greater frictional force - cyclist
- low streamlined body position over handle bars
- distance over the top is shorter than below bicycle
- air on top of cyclist travels at a slower speed
- creates higher pressure and a downward lift force
- allows tyres to maintain a firm grip on track
producing greater frictional force - skier
speed skiers must stay in contact with ice for faster speeds
- more downward lift means more force
- melts ice for a better friction free surface
