levers Flashcards
linear motion definition
motion of a straight or curved line where all body parts moving in the same distance, same speed in same direction
newtons first law of motion
law of inertia
if object is at rest, it will remain still
if it is moving in one direction, will continue to do so at the same velocity until a force is exerted upon it
the bigger the mass, the larger the inertia
means more force will be needed to change tis state of motion
if body changes state of motion it will stop, accelerate, decerlate etc
what is inertia
resistance an object has to a change in its state of motion
newtons second law of motion
law of acceleration
magnitude (size) and direction of the force applied to a body determines the magnitude (size) and direction of the acceleration given to the body
the rate of acceleration is directly porportional ti teg force causing the change
force=mass x acceleration
sport example of netons secon law of inertia
to accelerate at the start of their race, sprinter will need to require a large forec internally with their gluetals, quadricaps and hamstrongs as they drive forward
newtons third law of motion
law of reaction
desribes what happens when two bodies exert forces on one another
for every action(force) there is an equal and opposite reaction (force)
most questions involve the GRF (ground reaction force) force exerted on the ground by the body in contact with it
example of newtons third law of motion
sprinter pushes back on blocks as hard as possible (action) and the blocks push forward on the athlete (reaction) adn provides forward acceleration on the athlete
GRF what is it and sport example
GRF-force exterted on the ground by the body in contact with it
an individual standing still exerts a contact force (weight of the individual) and at the same time, equal and opposite GRF is exterted by the ground on the individual
law of inertia in example of football
n penalty, ball remains still (at rest) until it is kicked by the player (an external force is exerted upon it)
law of acceleration in example of football
when the player kicks the ball (force) during the game, the acceleration of the ball is prortional to the size of the force. Harder the player kicks the ball,the further and faster it will go in teh direction the force was applied
law of reaction
when footballer jumps up(action) to win a header, teh force is exerted on teh ground in order to gain height
same time, the ground exertes an upward force (equal and opposite reaction) to the player
scalar quantity
when a measurent is decsribed JUST in terms of its size and magnitude
direction is NOT taken into account
2 examples of scalar quantity measurements
speed and distance
speed definition and equation
speed-change in position
distance covered divided by time taken
distance definition and equation
length of the path a body follows from moving from one position to another
distance=speed xtime
equation triangle
D
S T
what is centre of mass
point of balance of the body
when would your centre of mass raise
when raise arms in air
what are the factors affecting stability
height of the centre of mass
position of the line of gravity
area of the support base
mass of the performer
study tip;HI PAM
height of the centre of mass
lowering centre of mass will increase stability
e.g lowering yourslef to tackle someone in rugby
position of the line of gravity
should be central over base of support to increase stability
what is the line of gravity
line exerting vertically downwards from the COM
area of the support base
more contact points, the larger the base of support becomes increasing stability
e.g a headstand has more contact points than a handstand so is a more balanced position
mass of the performer
greater the mass, more stability because of increased inertia
what happens when your COM starts to move to the edge of the base of support
makes a performer over balance
what does the fulcrum, reistance and effort act as
bones-acts as the levers
fulcrum-joints
effort-provided by the muscle
resistance-body part being moved
first class lever
fulcrum is located between the effort and resistance
movemnts of a first class lever
flexion and extension of the neck and head
JUST extension of the elbow
strudy tip: HEN
second class levers
where the resistance is between the fulcum and the effort
movemnt at second class lever
planatrflexion at the ankle
third class lever
effort is inbetween the resiatnce and the fulcrum
foudn in all other examined joints of the body
e.g hip, knee and elbow flexion
mechanical advantage
when the force arm is longer than the resistance arm
means can lift large load over short distance and requires little force
what is the force arm
length of line between where the fulcum and effort are labelled
study tip: write out EFL first two letters between are the force arm
second two letters are the resistance arm
mechanical disadvantage
where the reisatnce arm is longer in length than the force arm
means cannot move as heavy a load but can do it faster
