linear motion Flashcards
linear motion
linear motion
movement in a straight or curved line, eith all body parts moving in the same distance at the same speed in the same direction
scalar quantities
linear motion
when measurments are only described in terms of size or magnitude
mass (kg) , distance (m) , speed (m/s)
vector quantities
linear motion
when measurements are only described in terms of size or magnitude
weight, acceleration, displacement, velocity , momentum
mass
linear motion
mass is the quantity of matter the body posses
our mass is made up of bone, mucle, fat, tissue and fluid
kilograms (kg)
distance
linear motion
- distance is the length of the path a body follows when moving from one postion to another
- this is a scalar quantity as just measures size
displacment
linear motion
- is the length if a straight line joining the start and finish points
- is a vector quanity as it described the direction and mangnitude
speed
linear motion
- a measurment in metres/second of the bodys movement per unit of time with no reference of direction
- it is a scalor quantity since it does not consider direction
- SPEED = DISTANCE / TIME
SPEED EQUATION
linear motion
distance / time
velocity
linear motion
- measured in metres per second
- is the rate of change of displacement
- refers to how fast the body travels in a certain direction
- vector quantity
- VELOCITY = DISPLACEMENT (M) / TIME (S)
VELOCITY EQUATION
linear motion
displacement (m) / time (s)
stationary
distance time graph - look at graphs
- there is no distance travelled and the line is straight so therefore the object must be stationary
- e.g a netball player taking shot
acceleration
distance time graph - look at graphs
- now the line is curved and gradually gets steeper
- this shows that there is more distanced being covered
- this is showing acceleration
- e.g the first 20m of a 100m race
constant rate
distance time graph - look at graphs
- goes up in a constant diagonal direction
- indicates the distance ran is changing at a constant rate
deceleration
distance time graph - look at graphs
- the curve starts to leel off and less distance travelling in a certain amount of time
- means that deceleration is occuring
- e.g when a sprinter crosses the line
constant velocity
velocity time graph - look at graph
- line remains constant which indicates that they are travelling at a constant velocity
accelerating
velocity time graph - look at graph
- the gradient is steeper
- moving at a higher velocity/accelerating
- gradient = change is velcoity/time
decelerating
velocity time graph - look at graph
- line decreases
- the hits line
- comes to a stop
acceleration
- is a vector quantity
- is the measured in metres per second squared
- is the rate in change of velocity
- when velocity decreases , negative acceleration
- when velocity increases, postive acceleration
- ACCELERATION = FINAL VELOCITY - INITIAL VELOCITY / TIME
ACCELERATION EQUATION
final velocity - initial velocity /time
m/s2
momentum
- is the product of the mass and velocity of an object
- vector quanitity
- dependant upon mass and velocity - if one increases momentum increases
- momentum (kgm/s) = mass (kg) x velocity (m/s)
MOMENTUM EQUATION
mass (kg) x velocity (m/s)
KGM/S
forces
forces acting on a performer
- friction (static/slippage)
- air resistance
- gravity (9.8)
- water resistance
- a force changes the bodies state of motion
internal force
forces acting on a performer
- bodys muscles
- when our skeletal muscles contract
external force
forces acting on a performer
- comes from outside the body
- E.G firction , air resistance and weight
- gravity is also an exteral force but often descibed as weight
forces in linear motion
forces acting on a performer
- both interal and external forces act upon a performer during linear motion
- interal muscular forces allow the runner to contract their skeletal muscles to generate force to produce movement
- external force will act upon a runner
vertical forces (arrows going up and down)
forces acting on a performer - vertical forces
- weight due to gravity
- the greater the mass of the individual, the greater the weight of force pulling the body down
- reaction force
- whatever the force acting on the performer during linear motion, a reaction force will be generated
- newtons third law - every action has an equal and opposite reaction
weight equation
forces acting on a performer
- weight = mass (KG) x acceleration due to gravity
horizontal factors - arrows going away from body on floor
forces acting on a performer - horizontal
- frictional force - static and sliding
frictional force - static
forces acting on a performer - horizontal
- static friction force that is exerted when there is no motion between 2 surfaces
- E.G the friction generated bewteen the surface if a netball court and the shoe
- friction can be affected by - the surface characteristics of the two bodies in contact
- a 100m sprinter who wear running spikes - these help to increase friction as the spikes make contact with the track and therefore maximise accerlaeration
frictional force - sliding
forces acting on a performer - horizontal
- sliding friction force happens between two surfaces that are moving relative to eachother
- this is when 2 surfaces may have the redundancy to slip and slide
- the temperature of the two surfaces in contact can affect the friction
- E.G in curling, the ice is swept in front of the stone, the sweeping action raises the surface temperature of the ice which reduced the fricition between the stone and the ice, allowing the stone to travel further
air resistance
forces acting on a person
- opposes the motion of a body travelling through air depens on;
- the velocity of the moving person - the faster the performer moves , the greater the air resistance
- the corss sectional area of the moving body - the larger the cross sectional area, the greater air restiance
- E.G the postion of a cyclist during the tour de france - crouched low over the handlebars rather than sat upright
- the shape and surafce characteristic of the moving body - a streamlines shaped results in less resistance
- E.G most elite swimmers shave their body hair and wear a swimming cap to create a smooth surface
weight force arrow
forces acting on a person
- always drawn fown from the centre of mass
reaction force arrow
forces acting on a person
- starts from where the two bodies contact with one another
- goes up
friction arrow
forces acting on a person
- where the 2 bodies are in contact and is the opposite direction of any potential slipping
- goes forward away from the body
air resistance arrow
forces acting on a person
- drawn from the centre of mass opposing the direction of motion of the body
drawing force
forces acting on a person
- forces are vectors
- shown by using arrows
- the position, direction and lenght of arrown is important and need to be drawn accuratly
- the length of the arrown drawn reflects magnitude or size of the force
- the longer the arrow, the bigger the size of the force
net force - weight and reaction force
net force - weight and reaction force
- the resultant force acting of a body when all other forces have been considered
- net force is often discuessed in terms of balanced verus unbalanced forces
balanced force
net force - weight and reaction force
- is when tere are 2 or more forces acting on a body that are equal in size but opposite in direction
- E.G when standing , the weight force and reaction force are equal
- the net force is 0 , therfore no change in motion
unblanced force
net force - weight and reaction force
- when a force acting in one direction on a body is larger than a force acting in the opposite direction
- E.G when jumping, the performer accelerates upwards as the reaction force is bigger than weight force (weight force does not change on earth)
net force - friction and air resistance
net force - friction and air resistance
- if the friction arrow is equal in lenght to air resitance arrow - the net result is zero
- if the frcition arrow is longer than air resistance arrow the body will accerlerate
- if the friction arrow is shorter than the air resistance arrow the body will decelerate
net force - internal and external forces
net force - internal and external forces
- the effects of internal and external forces can be represented as a vecotr diagram
- LOOK AT DIAGRAM ON WORK
in high jump
net force - internal and external forces
- the performer uses a large internal muscular force from the legs to create action/reaction force
- to get the most vertical displacement (height) as possible
- the relationship between the amount of vertical force and hosizontal force provided by the mucles will lean towards the vertical component
- small horizontal force and large vertical force provided by the muscles will result in a high trajectory ( close to vertical)
in long jump
net force - internal and external forces
- trying to achieve as much horizontal displacement as possible
- greater contribution to the overall force from the horizontal component
- as a result of the application of these froces, the resultant forces for long jump can be dran as a vecotr diagram
impulse
relationship between impulse and momentum
- is the time it takes a force to be applied to an object or body
- can be calculated as force x time = impulse
- measures in newtons seconds (NS)
- an increase in impulse will result in an increase in the rate of change of momentum which will cause a large change in velocity
- impulse is the equivalent to a change in the momentum of a body as result of a force acting upon it - mass x velocity = momentum
- E.G when a tennis player follows through in a forehand, an increase in the amount of time the racket is in contact with the ball, this increases the outgoing momentum of the ball and will cause it to travel quicker
in a sporting environment (to add speed)
relationship between impulse and momentum
- impulse can be used to add speed to a body or object
- using impulse will increase momentum can be achieved by increasing the muscular force applied
- E.G in a basketball game, the amount of time an internal force is applied the higher a jump might be to get a defensive rebound
- E.G in the hammer throw, 3 or 4 turns are used to increase momentum to increase the distance as opposed to 1 turn
in a sporting evironment (to slow down)
relationship between impulse and momentum
- impulse can be used to slow down a body or object on impact
- using impulse to decrease the momentum a body occurs by increasing the time forces act upon them
- E.G in gymnastics, by bending at the knee , hip and ankle , extends the time of the force on the fround, controlling the gymnast , redicing momentum , reducing the chance of injury
- the longer the gymnast is in contact with the mat the more mometum is reduced
interpretation of impulse graphs
relationship between impulse and momentum
- as the spinter foot lands on the ground , their mucles contract and a force is applied into the ground (action force) and the ground reaction force then acts on the foot which allows the spinter to accelerate
- the action of the foot in contact with the ground is refered to as a single footbfall
- it is impostant to note that when running, negative impulse occurs first when the foot lands to privide breaking action
- the positive impulse occurs next as the foot takes off for acceleration
- above the line = postive impulse
- below the line = negative impulse
accelerating
relationship between impulse and momentum
- LOOK AT DIAGRAM
- the net impulse is postive which shows the sprinter is accelerating
- start of the race after leaving the blocks
middle of the race
relationship between impulse and momentum
- LOOK AT DIAGRAM
- here both postive and negative impulses are equal
- net impulse is zero
- this means there is no acceleration or deceleration so the sprinter is running at constant velocity
- middle of the race
towards the end of the race
relationship between impulse and momentum
- LOOK AT THE DIAGRAM
- here the net impulse is negative which shows the sprinter is decelerating
- towards the end of the race
