Limear Motion, Angular Motion, Fluid Mechanics And Projectile Motion

Question 1

What is linear motion

Answer 1

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

Question 2

What is the definition, equation and unit of measurement for distance

Answer 2

Total length of path covered from start to finish

Measured

Meters (M)

Question 3

What is the definition, equation and unit of measurement for speed

Answer 3

Rate of change in distance

Speed=distance/time taken

M/s

Question 4

What is the definition, equation and unit of measurement for displacement

Answer 4

Shortest straight-line route from start to finish

Measured

Meters (M)

Question 5

What is the definition, equation and unit of measurement for velocity

Answer 5

Rate of change of displacement

Velocity=displacement/time taken

M/s

Question 6

What is the definition, equation and unit of measurement for acceleration/ deceleration

Answer 6

Rate of change in velocity

Acceleration= (final velocity-initial velocity)/ time taken

M/s/s

Question 7

What does a distance time graph look like during: rest, acceleration, constant speed, deceleration

Answer 7

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)

Question 8

What do speed/ time graphs look like at constant speed, acceleration, deceleration

Answer 8

Constant speed: flat horizontal line

Acceleration: non linear increased curved line

Deceleration: non linear decreased curved line (starts from high on Y axis)

Question 9

What does a velocity/time graph show

Answer 9

The velocity over a period of time, gradient of curve indicates acceleration or deceleration of the body

Question 10

What is angular motion

Answer 10

Movement of a body or part of a body in a circular path about an axis of rotation

Question 11

What does angular motion results from

Answer 11

An eccentric force applied to body (a force applied outside the CoM)

Question 12

What is torque

Answer 12

A measure of the turning (rotational or eccentric) force applied to the body

Question 13

Give the location and an example of longitudinal axis of rotation

Answer 13

Location: runs from the top to bottom of the body

Trampolinist performs a full twist turn

Question 14

Give the location and an example of transverse axis of rotation

Answer 14

Location: runs from side to side of the body

A front somersault

Question 15

Give the location and example of frontal axis of rotation

Answer 15

Location: runs from front to the back of the body

A gymnast performs a cartwheel

Question 16

Give the definition, equation and unit of measurement for moment of inertia

Answer 16

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

Question 17

Give the definition, equation and unit of measurement for angular velocity

Answer 17

The rate of change in angular displacement or rate of rotation

Angular velocity= angular displacement/time taken

Rad/s

Question 18

Give the definition, equation and unit of measurement for angular momentum

Answer 18

The quantity of angular motion possessed by a body or part

Angular momentum= moment of inertia X angular velocity

Kgm^2/s

Question 19

What factors affect the size of moment of inertia of a rotating body

Answer 19

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

Question 20

What effect does MI have on angular velocity

Answer 20

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

Question 21

What is angular analogue of Newton’s first law of motion

Answer 21

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

Question 22

What is conservation of angular momentum

Answer 22

Angular momentum is a conserved quantity that remains constant unless an external force or torque is applied

Question 23

Describe what happens to an ice skater in performing a triple axel jump in ice skating

Answer 23

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

Question 24

What 4 factors affect air resistance and drag

Answer 24

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

Question 25

Give examples for each factor affecting air resistance or drag

Answer 25

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

Question 26

What factors affect the horizontal distance travelled by a projectile

Answer 26

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

Question 27

What is a parabolic flight path, what’s it caused by

Answer 27

A flight path symmetrical about its highest point Caused by dominant weight forge of a projectile eg shot put

Question 28

What is a non parabolic flight path, what is it caused by

Answer 28

A flight path asymmetrical about its highest point Caused by dominant force of air resistance on a projectile eg discus

Question 29

Draw a free body diagram for a shot put

Answer 29

W from COM Is larger arrow than AR from CoM, DoM as a dotted line from CoM on same path as AR

Question 30

Draw a free body diagram for a shuttle cock

Answer 30

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

Question 31

How do you draw a parallelogram of forces

Answer 31

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

Question 32

What is the Bernoulli principle

Answer 32

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

Question 33

What does an aerofoil shape have

Answer 33

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

Question 34

What results from an aerofoil shape

Answer 34

As velocity increases, pressure decreases Additional lift force created due difference in pressure Angle of attack also taken into account

Question 35

Draw a air flow diagram of a discus

Answer 35

Discus at roughly 30degree angle DoM opposing airflow heads High velocity low pressure towards tilted end Low velocity high pressure (barely affected) opposing side

Question 36

Where is the eccentric force applied and how projectile spins for top spin

Answer 36

Above CoM, downwards around the transverse axis

Question 37

Where is the eccentric force applied and how projectile spins for backspin

Answer 37

Below CoM, upwards around the transverse axis

Question 38

Where is the eccentric force applied and how projectile spins for side spin hook

Answer 38

Right of CoM, left around longitudinal axis

Question 39

Where is the eccentric force applied and how projectile spins for side spin slice

Answer 39

Left of CoM, right around longitudinal axis

Question 40

What is magnus force

Answer 40

A force created from a pressure gradient on opposing surfaces of a spinning body moving through the air

Question 41

For a tennis ball with top spin, describe the additional magnus forge created

Answer 41

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

Question 42

What are the benefits of spin

Answer 42

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

Question 43

Give air flow diagram for tops in

Answer 43

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

Question 44

Give air flow diagram for hook

Answer 44

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

Question 45

Give the description of an air flow diagram for a slice

Answer 45

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