Limear Motion, Angular Motion, Fluid Mechanics And Projectile Motion Flashcards
What is linear motion
Movement of a body in a straight line or curved line where all parts move the same distance in the same direction over the same time
What is the definition, equation and unit of measurement for distance
Total length of path covered from start to finish
Measured
Meters (M)
What is the definition, equation and unit of measurement for speed
Rate of change in distance
Speed=distance/time taken
M/s
What is the definition, equation and unit of measurement for displacement
Shortest straight-line route from start to finish
Measured
Meters (M)
What is the definition, equation and unit of measurement for velocity
Rate of change of displacement
Velocity=displacement/time taken
M/s
What is the definition, equation and unit of measurement for acceleration/ deceleration
Rate of change in velocity
Acceleration= (final velocity-initial velocity)/ time taken
M/s/s
What does a distance time graph look like during: rest, acceleration, constant speed, deceleration
Rest: straight horizontal line
Acceleration: non linear increased curved line
Constant speed: straight diagonal line
Deceleration: non linear curved decreased line (starts from low on Y axis)
What do speed/ time graphs look like at constant speed, acceleration, deceleration
Constant speed: flat horizontal line
Acceleration: non linear increased curved line
Deceleration: non linear decreased curved line (starts from high on Y axis)
What does a velocity/time graph show
The velocity over a period of time, gradient of curve indicates acceleration or deceleration of the body
What is angular motion
Movement of a body or part of a body in a circular path about an axis of rotation
What does angular motion results from
An eccentric force applied to body (a force applied outside the CoM)
What is torque
A measure of the turning (rotational or eccentric) force applied to the body
Give the location and an example of longitudinal axis of rotation
Location: runs from the top to bottom of the body
Trampolinist performs a full twist turn
Give the location and an example of transverse axis of rotation
Location: runs from side to side of the body
A front somersault
Give the location and example of frontal axis of rotation
Location: runs from front to the back of the body
A gymnast performs a cartwheel
Give the definition, equation and unit of measurement for moment of inertia
Resistance of a body to change its angular motion or rotation
Moment of inertia= sum (mass x distribution of mass from axis of rotation ^2)
KgM^2
Give the definition, equation and unit of measurement for angular velocity
The rate of change in angular displacement or rate of rotation
Angular velocity= angular displacement/time taken
Rad/s
Give the definition, equation and unit of measurement for angular momentum
The quantity of angular motion possessed by a body or part
Angular momentum= moment of inertia X angular velocity
Kgm^2/s
What factors affect the size of moment of inertia of a rotating body
Mass: greater the mass, the greater the MI
Distribution of mass from axis of rotation: further the mass moves from axis of rotation, the greater the MI
What effect does MI have on angular velocity
If MI is high, resistance to rotation is high, therefore angular velocity is low; the rate of spin is slow
If MI is low, resistance to rotation is low, angular velocity is high; rate of spin is fast
What is angular analogue of Newton’s first law of motion
A rotating body will continue to turn about an axis of rotation with constant angular momentum unless acted upon by an eccentric force or external torque
What is conservation of angular momentum
Angular momentum is a conserved quantity that remains constant unless an external force or torque is applied
Describe what happens to an ice skater in performing a triple axel jump in ice skating
At take off: angular momentum generated by applying eccentric force from ice to the body, rotation starts about longitudinal axis, distribution of mass is away from longitudinal axis, MI is high, angular velocity is low
During flight: mass distribution closer to longitudinal axis, MI decreases, angular velocity increases, ice skater spins quickly
Landing: mass distributed away from longitudinal axis, MI increases, angular velocity decreases, ice skater applies external torque to remove conserved quantity of angular motion possessed
What 4 factors affect air resistance and drag
Velocity: greater the velocity greater the force of air resistance
Frontal cross sectional area: greater the area the greater the air resistance
Streamlining and shape: more aerodynamic the shape of body the lower the air resistance or drag
Surface characteristics: the smoother the surface the lower the air resistance or drag
Give examples for each factor affecting air resistance or drag
Velocity: track cyclist greatly affected by increased velocity
Frontal cross sectional area: low crouched position of downhill skier
Streamlining and shape: streamlined body shape out of a tumble turn in swimming reduces drag
Surface characteristics: swimmers were special suits to minimize drag
What factors affect the horizontal distance travelled by a projectile
Speed of release: due to Newton’s second law, greater outgoing speed of projectile, further it will travel
Angle of release: 45 degree angle is optimal for distance
Height of release: 45degree is optimal angle if height and landing heights are equal (if release height greater angle lower than 45 is better, other way round etc)
Aerodynamic factors: Bernoulli and magnus
What is a parabolic flight path, what’s it caused by
A flight path symmetrical about its highest point
Caused by dominant weight forge of a projectile eg shot put
What is a non parabolic flight path, what is it caused by
A flight path asymmetrical about its highest point
Caused by dominant force of air resistance on a projectile eg discus
Draw a free body diagram for a shot put
W from COM Is larger arrow than AR from CoM, DoM as a dotted line from CoM on same path as AR
Draw a free body diagram for a shuttle cock
DoM is dotted line from CoM, AR on same path as DoM from CoM and larger arrow than W, W from CoM going straight down
How do you draw a parallelogram of forces
Draw free body diagram showing W and AR
Add broken parallel lines to W and AR to create parallelogram
Draw diagonal line from origin of W and AR (CoM) to opposite corner and draw double arrow on line named resultant force
What is the Bernoulli principle
Creation of additional lift forge on a projectile in flight resulting from Bernoullis conclusion that the higher the velocity of air flow, the lower the surrounding pressure
What does an aerofoil shape have
A curved upper surface, forcing air flow to travel further distance and therefore move at a higher velocity
A flat underneath surface that allows air to travel a shorter distance at a lower velocity
What results from an aerofoil shape
As velocity increases, pressure decreases
Additional lift force created due difference in pressure
Angle of attack also taken into account
Draw a air flow diagram of a discus
Discus at roughly 30degree angle
DoM opposing airflow heads
High velocity low pressure towards tilted end
Low velocity high pressure (barely affected) opposing side
Where is the eccentric force applied and how projectile spins for top spin
Above CoM, downwards around the transverse axis
Where is the eccentric force applied and how projectile spins for backspin
Below CoM, upwards around the transverse axis
Where is the eccentric force applied and how projectile spins for side spin hook
Right of CoM, left around longitudinal axis
Where is the eccentric force applied and how projectile spins for side spin slice
Left of CoM, right around longitudinal axis
What is magnus force
A force created from a pressure gradient on opposing surfaces of a spinning body moving through the air
For a tennis ball with top spin, describe the additional magnus forge created
Upper surface of ball rotating towards oncoming air flow, opposing motion, decreasing velocity of air flow and creating a high pressure zone
Lower surface of ball rotating same direction as air flow, increasing velocity of air flow and creating zone of low pressure
Pressure grading forming and an additional Magnus force being created downwards
What are the benefits of spin
Gives hall stability in flight
Use of top spin shortens flight path, allowing ball to be hit harder but still lane in play
Can confuse opposition
Give air flow diagram for tops in
If DoM is going right:
Ball rotating clockwise
MF from CoM going down
Air flow lines affected beneath the ball creating high velocity/ low pressure area
Give air flow diagram for hook
If DOM is up the page:
Ball rotating anti clockwise
MF from CoM goes left
Left side of ball affected, creating high velocity of airflow/ low pressure area
Give the description of an air flow diagram for a slice
Air flow opposes motion
Ball rotates to the right, guiding air flow (high velocity/low pressure)
Ball rotated against air flow on left side, resisting air flow (high pressure/low velocity)
Pressure gradient is former
MF acts to deviate flight path to the right
