Linear / Angular Motion Flashcards
What is Newtons law of Linear Motion
Linear motion is motion in a straight or curved line
This all body parts moving at the same speed in the same direction
What’s a scalar quantity
Has only magnitude
What’s a vector quantity
Has both magnitude and direction
What is weight
Force on a given mass due to gravity. Measured in Newtons (N) its a unit of force. To calculate weight; mass X gravity = weight.
Weight is a vector
What is distance
Measured in metres. The path a body takes as it moves from the starting to finishing position.
It’s a scalar quantity
What is displacement
Measured in metres. Shortest route in a straight line between start and finish position.
Vector quantity
What is speed
Scalar
Can be defined as the rate of change of a position
Can be calculated:
Speed = distance/time
What’s velocity
How fast a body travels in a certain direction.
Displacement/ time
What is acceleration
The rate of change of velocity
When velocity increases, positive acceleration occurs. When velocity decreases, negative acceleration occurs.
Av acceleration = change in velocity/ time
What is momentum
The product of mass and velocity of an object.
Momentum(Kim/s) = mass x velocity
It is a vector
What is conservation of momentum
Momentum can also be conserved.
This occurs when a performer or object is in flight. When in flight neither mass nor velocity can be altered.
Mass is constant (unchanged).
Velocity can only be altered by external forces Such as gravity and air resistance.
What is a force and what are the two types
A force will change a body’s state of motion.
There are 2 types of force;
-Internal Force: Generated by the skeletal muscle
-External Force: Comes from outside the body
What’s internal forces
Generated by the skeletal muscle
E.g The force here is generated by the gastrocnemius, quadriceps and gluteals that contract concentrically to plantarflex the ankle & extend the knee and hip in a jump.
What is external forces
Comes from outside the body
For example:
Friction, air resistance and weight.
Gravity is an external force, but is described as weight. Weight is the gravitational force that pulls a body downwards.
What is vertical forces
Gravity / weight and reaction
What’s horizontal forces
Friction and air resistance
What’s reaction force
there is always a reaction force when two bodies are in contact with each other.
What does static mean in horizontal force
Force exerted when there is no motion between 2 surfaces
What does sliding mean in horizontal forces
When 2 bodies in contact have a tendency to slip/slide over.
E.g running
Where are the friction arrows drawn
friction opposes motion, an arrow is therefore drawn in the opposite direction to the slipping, usually in the same direction as the motion.
What is friction affected by
The roughness of the surface: The rougher the surface, the greater the friction. Athletics spikes increase friction; maximise acceleration.
2) The mass of an object: The greater the mass, the greater the friction: Think mountain biking, up a muddy hill; stand up over front driving wheel for better grip!
3) Temperature of the 2 surfaces: Increase in temperature, reduces the friction. Think about sweeping in curling.
What is air resistance
A force that acts in the opposite direction to the motion of a body travelling through the ai
What is air resistance affected by
The velocity of the moving body:
The faster an object is moving, the more it is subject to air resistance.
The frontal cross-sectional area of the moving body:
The larger the cross sectional the greater the effects of air resistance.
3) The shape and surface characteristics of the moving body:
Streamlined shape = less resistance, as does a smooth surface.
What is friction
a force starts from where the 2 bodies are in contact and is opposite to the direction of any potential slipping. It is drawn in the same direction as motion.
What is net force
This is the resultant force acting on a body when all other forces have been considered.
Net force is often discussed as balanced / unbalanced forces.
What happens when friction is more than air resistance
Acceleration
How can a high jumper be represented in a vector
A high jumper will generate a large internal force from the muscles in the leg to create a big reaction force. This will help them achieve vertical displacement (height).
Steep line
How can a long jumper be represented in a vector diagram
A long jumper will generate a large internal force from the muscles in the leg to create a large horizontal force to generate a large horizontal distance.
Less steep line
Sketch a force time graph for the start middle and end of a race
How is impulse linked to momentum
If the impulse increases so to does the rate of change of momentum.
This will cause a large change in velocity.
How can the performer use impulse to increase speed
Increase the amount of internal muscular force applied.
2) Increase the amount of time in which the force is applied (E.G: hammer spin, 3-4 times in circle)
How can the performer use impulse to decrease speed
Increase the time that a force acts on the body/object.
E.G: Absorbing landing in gymnastics.
E.G: Pushing feet into ground at end of 60m sprint.
What does angular motion refer to
Angular motion is movement of a body in a circular path around an axis of rotation
It refers to rotation.
ST FS TL
Angular motion can involve the whole body Or just an arm or leg
When does angular motion occur
Angular motion occurs when a force is applied
outside the centre of mass.
An off-centre force is referred to as an eccentric force.
What’s an eccentric force
A force applied outside the centre of mass
What are the axis of rotation
Transverse
Sagittal
Longitudinal
What movement is sagittal axis
Stomach
Cartwheel
What movement is transverse axis
Side to side
Somersault
What movement is with the longitudinal axis
Top to bottom
Ice skating spin
What is a Torque (moment of force)
Torque is the turning force.
It causes an object to turn about its axis of rotation. It is dependant on 2 things
1) The greater the size of the force the greater the torque.
2) Application of the same force further away from the axis will increase torque
How to increase the moment of force
It depends of where you apply the force
If you exert a force close to he fulcrum you have to apply a greater force
How to calculate the moment of force/ torque (Nm)
Force (N) X perpendicular distance from fulcrum (M)
The moment of force can either be an effort or resistance arm
What’s Newton’s first law of angular motion
Every body continues in it’s state of rest or will turn about its axis of rotation unless changed that state by an external force (torque) acting upon it
How to calculate angular momentum
Moment of inertia x angular velocity
What is moment if inertia
Moment of inertia is the resistance of a body to change it’s state of angular motion or rotation
What is factors affecting moment of inertia
Mass - greater mass = greater moment of inertia
Distribution of mass from axis - Further distribution of mass from axis = greater MI
closer = smaller MI
What is the relationship between moment of inertia and angular velocity
If moment of inertia is low angular velocity is high
If moment of inertia is high angular velocity is low
What’s Newton’s second law of angular motion
The rate of change of angular momentum (acceleration) of a body is proportional to the force (torque) causing it and the change that takes place in the direction which the force (torque) acts.
What’s Newton’s third law of angular motion
When a force (torque) is applied by one body to another, the second body will exert an equal and opposite force (torque) on the other body
What’s angular displacement
This is the smallest change in angle between the starting and finishing point.
What’s angular displacement measured in
Angular displacement is measured in degrees or radians 1 radian = 57.3 degrees
What’s angular velocity
Refers to the rotational speed of an object and the axis about which the object is rotating.
How is angular velocity calculated
Angular velocity (rad/s) = Angular displacement (rad) /Time taken (s)
What is angular acceleration and how is it calculated
Angular acceleration is the rate of change of angular velocity
Angular acceleration (rad/s2) =
Change in angular velocity (rads/s) / Time taken (s)
What’s projectile motion
Refers to the movement of either an object (shot/shuttle) or the human body as it travels through the air.
Factors affecting horizontal displacement of a projectile
Angle of release
Velocity of release
Height of release
How does the angle of release determine the horizontal displacement of a projectile
Where release height and landing are the same: optimum = 45 degrees.
Where release height is greater than landing height: optimum = less than 45 degrees
Where release height is below landing height: optimum = greater than 45 degrees
What is the relationship between velocity and horizontal displacement
An increase in velocity will increase horizontal displacement
What are the factors that affect flight paths of different projectiles
Weight and air resistance
Describe the flight of a shot put
With shot put, it has a large mass so the weight arrow is longer than air resistance.
Air resistance has small arrow
Describe the flight of a shuttlecock
it is affected by air resistance Object veers away from parabolic path
Forms an asymmetrical or distorted parabola
shuttle starts off with high velocity due to force of racket.
What’s a dynamic fluid force
Concerned with the movement of liquids and gases. - Drag and lift are dynamic fluid forces.
What is a drag force
A drag force will slow something down.
• Drag is a resistance force.
• Drag is caused by a body travelling through a fluid.
A drag force will slow something down.
• Drag is a resistance force.
• Drag is caused by a body travelling through a fluid.
• Drag acts in opposition to the direction of motion.
• Drag has a negative effect on velocity.• Drag acts in opposition to the direction of motion. • Drag has a negative effect on velocity.
What’s surface drag
Friction between surface of an object and the fluid environment”
What’s Form drag
Relates to the impact of the fluid environment on an object……Forces affecting the leading edge of an object increases form drag……Forces affecting the trailing edge of an object reduces form drag”
Relates to streamlining
What’s streamlining
Shaping a body so it can move through fluid effectively and quickly.
Streamlined bodies incorporate a ‘gradual taper’.
The streamlined shape allows air to move past in layers. Enables air to flow smoothly.
Reduces fluid drag.
What’s turbulent flow
flow in which the fluid undergoes irregular fluctuations, or mixing, constantly undergoing changes in magnitude and direction.
It increases friction & fluid drag and decreases velocity.
What’s laminar flow
Layers of fluid flow slide smoothly over one another. They undertake smooth paths, or layers.
Less resistant to movement.
Factors that affect air resistance
Velocity of the moving body.
2) The cross-sectional area of the moving body.
3) The shape/surface of the moving body.
How do cyclists decrease drag / increase velocity
Helmet: designed to encourage laminar flow.
Bike: lightweight carbon fibre frame, aerodynamic features.
Body position: Head over the bars, low over front wheel, arms tucked.
Clothing: Compressed clothing.
