biomechanics Flashcards
what is newton’s first law of motion?
The Law of Inertia
What is the law of Inertia?
Inertia is the resistance of a body to change its state of motion, wether at rest or while moving
What is force?
Force is a push or pull that alters the state of motion of a body
describe inertia
‘A body continues in a state of rest or uniform velocity unless acted upon by an external or unbalanced force’
what happens if the mass is greater? NL1
The greater the mass of a body the greater the force needed to overcome inertia and create motion
what is newton’s second law of motion?
The law of acceleration
what is the law of acceleration?
‘A body’s rate of change in momentum is proportional to the size of the applied and acts in the same direction as the force applied’
What is momentum?
This is the quantity of motion possessed by a moving body and is closely related to acceleration.
what is newton’s third law?
the law of reaction
what is the law of reaction
for every action force applied to a body, there is an equal and opposite reaction force
what are the 4 key concepts which can be ascertain the quantities of force and movement achieved?
- velocity
- Momentum
- Acceleration
- Force
what unit do you use for velocity?
1 m/s
what is velocity?
velocity is the rate of change in displacement.
what is displacement?
Displacement is the strongest straight line route between start and finish points
what is the velocity equation?
Velocity (m/s) = displacement (m) /time taken (s)
how to calculate momentum?
Momentum(kg m/s)= mass(kg) x velocity(m/s)
What is the acceleration equation?
Acceleration(m/s/s)=final velocity- initial velocity (m/s))/time taken(s)
what is the force equation
Force(N)= mass(kg) x acceleration (m/s/s)
what are the two types of force?
internal force and external force
What are the five effects of force?
creates motion, Decelerate a body, change direction of a body, change shape of a body, accelerate a body
what is internal force
generated by the contraction of skeletal muscle
what is external force
comes from outside the body and acts upon it
explain creates motion
a football will remain at rest on the penalty spot until a force is applied to make it move
explain decelerate a body
as the ball moves through the air towards goal, the force of air resistance will act in the opposite direction and slow it down
explain change direction of a body
as the goalkeeper dives to save a high corner shot, he will apply a force from his hands to the ball, changing its direction and pushing it away from goal
explain change shape of a body
if the goalkeeper fails to make the save, the force of the ball coming into contact with the net will make the net change shape
explain accelerate a body
the greater the force applied by the footballers foot to the ball, the greater the rate of acceleration towards the goal
what is net force?
The sum of all forces acting on a body
if net force is 0…
- remain at rest
2. travel with constant velocity
if net force is 0 the forces are…
balanced
net force is present…
there is a change in motion and forces are unbalanced
if net force is positive a body will…
accelerate
if net force is negative a body will…
decelerate
what is the equation for weight?
Weight(N) = mass(kg) x acceleration due to gravity (m/s/s)
name two vertical forces?
weight and reaction
what is weight
the gravitational pull that the earth exerts on a body, measured in Newtons(N)
what is reaction?
the equal and opposite force exerted by a body in response to the action force placed upon it, measured in Newtons (N)
name two horizontal forces?
friction and air resistance
what is friction
the force that opposes the motion of two surfaces in contact and is measured in Newtons
what are the factors affecting friction?
- Roughness of the ground surface
- Temperature
- roughness of the contact surface
- size of normal reaction
explain roughness of the ground surface
increased roughness leads to increased friction. eg an athletics track
explain temperature affecting the amount of friction
increasing the temperature friction is increased eg f1 drivers on a warm up lap
roughness of the contact surface affecting friction
a rougher contact surface leads to increased friction. eg sprinter wearing spikes
size of normal reaction affecting friction
by increasing normal reaction friction is increased. eg shot putters have high mass due to newton’s third law
what are the factors affecting friction?
- velocity
- shape
- frontal cross-sectional area
- smoothness of contact surface
by increasing velocity air resistance…
increases eg the greater the velocity of a sprint cyclist the greater the air resistance opposing the motion
an aerodynamic shape leads to?
lower air resistance eg sprint cyclists helmet
