Biomechanics

Question 1

What is linear motion? [4]

Answer 1

• motion in a straight or curved line
• all body parts moving in the same direction
• speed
• and distance

Question 2

Explain using an example Newton’s 1st law of linear motion. [4]

Answer 2

• law of inertia
• every body continues its state of rest or motion
• unless compelled to change that state by external forces acting upon it
• a football when placed for a penalty will not move until the player puts force on it by kicking it

Question 3

Define inertia. [1]

Answer 3

the resistance an object has to a change in state or motion

Question 4

State Newtons 2nd law of linear motion. [4]

Give an example.

Answer 4

• law of acceleration
• the magnitude and direction of the force determines the magnitude and direction of acceleration
• force=mass x acceleration
• If a player kicks a football with large amounts of force to wards the goals the ball will travel fast and towards the goal

Question 5

State and give an example of Newton’s 3rd law of linear motion. [4]

Answer 5

• law of action/reaction
• for every force there is an equal and opposite reaction
• the harder a player pushes against the ground the further they will go off the ground
• this is ground force reaction

Question 6

What is the difference between a vector and a scalar quantity. [2]

Answer 6

vector quantities have magnitude and direction

scalar quantities only have magnitude

Question 7

Define distance. [3]

Answer 7

path the body takes as it moves from starting point to finishing point
scalar
metres

Question 8

What is the difference between speed and velocity [4]

Answer 8

speed is a scalar quantity
body’s distance moved per unit of time

velocity is a vector quantity
rate and direction of change in position of displacement

Question 9

what is the equation for

a. speed
b. mass
c. weight

Answer 9

distance/time
volume x density
mass x gravity

Question 10

Compare mass and weight. [3]

Answer 10

mass is scalar
kg
quantity of matter a body possesses

weight is vector
N
force on a given mass due to gravity

Question 11

Define angular motion [1]

Answer 11

rotation around a fixed point or axis

Question 12

Apply Newton’s 2nd law to angular motion [1]

Answer 12

the rate of change pf angular motion of a body is proportional to the torque causing it and the change that takes place in the direction in which the torque acts.

Question 13

Apply Newton’s 3rd law of motion to angular motion [1]

Answer 13

for every torque there is an equal and opposite torque

Question 14

What effects an objects moment of inertia during angular motion [4]

Answer 14

the resistance a body has to angular motion

velocity (more velocity=less inertia)

mass of body (bigger mass=bigger inertia)

distribution of mass (closer to the axis of rotation the lower the inertia)

Question 15

What is a radian [2]

Answer 15

measure of of angles

equal to 57.3 degrees

Question 16

Explain what is meant by drag. [4]

Answer 16

a resistance force caused by the motion of a body travelling through a fluid (air/water)

acts in the opposite direction to motion

it has a negative affect on velocity

produced from air resistance and friction

Question 17

What things affect drag? [6]

Answer 17

velocity
the more velocity the more drag

cross sectional area
a larger area will increase drag

shape and surface
the more stream lined and aerodynamic the less drag

Question 18

Explain how a cyclist might reduce drag [4]

Answer 18

stream line-shape body to move effectively through air

tuck elbows and handle bars in to reduce cross sectional area

bend down to reduce cross sectional area

wear tight clothing to reduce surface drag

Question 19

What are the two types of drag [4]

Answer 19

surface- friction between the surface of an object and the environment

form- impact of fluid environment on object

Question 20

Explain a factor that affect drag [2]

Answer 20

velocity- speed increases air resistance

cross sectional area- increases air resistance in more places

shape and surface- smoother surfaces decrease drag

Question 21

Define lift force [1]

Answer 21

causes a body to move perpendicular to the direction of travel

Question 22

How will a lift force effect a projectile [2]

Answer 22

• the more lift force a projectile has during flight the longer it will stay in the air
• and the further horizontal distance of travel

Question 23

Explain Bernoulli’s principle and how it creates an upward force [4]

Answer 23

• air molecules exert less pressure the faster they travel
• and more pressure the slower they travel
• air above a projectile motion is moving faster therefore has a lower pressure than those below the projectile motion
• this creates an upward force

Question 24

What is the optimum angle of attack for a discus [1]

Answer 24

25-40 degrees

Question 25

Explain how a downwards lift force can be created [4]

Answer 25

- want the air below the object to be travelling faster - they will have less air pressure - creating a downwards force - Bernoulli's principle - 140-155 degrees

Question 26

Define the term centre of mass [1]

Answer 26

point of balance | point of concentration of mass

Question 27

Explain how the position of centre of mass will affect performance [3]

Answer 27

position affects stability if centre of mass is off centre then stability will reduced if unstable performance will deteriorate

Question 28

State 4 ways to increase stability [4]

Answer 28

lower the centre of mass line of gravity to be central larger base support mass of performer

Question 29

Explain one way to increase stability [2]

Answer 29

lower the centre of mass bend knees, smaller line of gravity to be central stand straight larger base support both feet on ground, wider mass of performer increased inertia

Question 30

Explain how centre of mass will affect a rugby tackle [5]

Answer 30

wants to remain stable and not fall to the ground bend knees keep body straight have both feet on the ground, spread slightly apart have more mass as this will increase performers inertia

Question 31

Give an example of a first class lever in the body. [1]

Answer 31

head/neck flexion and extension | elbow extension

Question 32

Describe a second class lever include and example [4]

Answer 32

``` load is in the middle of the fulcrum and the effort planta flexion generate large amounts of force has to lift up whole body weight slow and limited range of movement ```

Question 33

Explain where we would see a mechanical advantage [1]

Answer 33

effort arm is longer than load arm

Question 34

Describe a 3rd class lever with an example [5]

Answer 34

``` effort in the middle of fulcrum and load hip, knee and elbow flexion has a large range of movement resistance can be moved quickly little force created ```

Question 35

State whether the following are 1st,2nd or 3rd class levers a. elbow flexion b. elbow extension c. plantar flexion d. neck extension e. knee flexion

Answer 35

a. 3rd b. 1st c. 2nd d. 1st e. 3rd

Question 36

Using examples in your answer explain the differences between internal forces and external forces [4]

Answer 36

external forces come from outside of the body e.g. friction/air resistance/gravity/weight internal forces are generated by the skeletal muscles quadriceps contract to extend the knee

Question 37

Describe an example of a vertical force [3]

Answer 37

weight the gravitational force exerted by an object weight = mass x acceleration

Question 38

Describe friction. [4]

Answer 38

occurs when two or more bodies are in contact with each other static- no movement sliding - movement affected by surface characteristics/ temperature/ mass/ cross sectional area air resistance

Question 39

Define air resistance and the factors that affect it [3]

Answer 39

a force that acts in the opposite direction to motion velocity cross sectional area shape and surface

Question 40

Describe the forces acting on a runner accelerating [6]

Answer 40

- weight is pulling runner down towards the ground - reaction force is when the ground pushes off upwards against the foot - weight is equal to the reaction force - air resistance is pushing against player in the opposite direction to the player running - friction occurs when foot and ground are in contact and acts in direction runner is moving - friction is greater than air resistance - it is an unbalanced force - net force is in direction of motion

Question 41

What three factors affect horizontal displacement [3]

Answer 41

angle of release speed of release height of release

Question 42

Define projectile motion [1]

Answer 42

the movement of an object or human body as they travel through the air

Question 43

What are the optimum angles of release in the following situations [4] release height (RH) = landing height (LH) RH < LH RH>LH shotput

Answer 43

1. 45 degrees 2. more than 45 degrees 3. less than 45 degrees 4. 26-38

Question 44

Explain how the speed of release affects horizontal displacement [1]

Answer 44

the more velocity the greater the horizontal displacement

Question 45

How does the height of release affect horizontal displacement [1]

Answer 45

the higher the release height the greater the horizontal displacement

Question 46

What two factors affect the flight path of a projectile [2]

Answer 46

air resistance | mass

Question 47

What is the difference between a true parabola and distorted parabola [2]

Answer 47

true = matching left and right hand sides | distorted- sides aren't matching

Question 48

Explain why a shotput follows a true parabolic path [2]

Answer 48

large mass | less air resistance

Question 49

Explain why a shuttlecock has a distorted parabolic path [2]

Answer 49

less mass | and greater air resistance

Question 50

Describe the vectors of a parabolic flight [3]

Answer 50

1 large positive vertical component as it travels upwards 2 reaches max height and there is no vertical components 3. larger negative vertical component as it falls before hitting the ground

Question 51

Define acceleration [2]

Answer 51

rate of change in velocity m/s2

Question 52

Runner starts at start line not moving. Reach speed of 10m/s in 5 seconds. what is there acceleration [1]

Answer 52

(final-initial velocity)/time (10-0)/5 2m/s2

Question 53

Define momentum [2]

Answer 53

product of mass and velocity of an object kgm/s

Question 54

A runner weighs 50 kg. They are running at a speed of 10 m/s. Calculate their momentum [1]

Answer 54

kgm/s= kg x m/s 50x10 500kgm/s

Question 55

How can momentum be conserved? [3]

Answer 55

object in flight both mass and acceleration can be altered unless external force acts upon it

Question 56

define net force [1]

Answer 56

the resultant force acting on a body when all other forces have been considered

Question 57

What is a balanced force [1]

Answer 57

2 or more forces acting on a body that are equal in size | but opposite in direction

Question 58

What is a vector [2]

Answer 58

have magnitude and direction | when drawing the bigger the arrow the greater the force

Question 59

Draw a vector of a high jumper [1]

Answer 59

arrow up is longer than horizontal line

Question 60

Give an example of a balanced force [1]

Answer 60

standing still | air resistance is equal friction

Question 61

Define impulse [1]

Answer 61

the time it takes for a force to be applied

Question 62

what is the equation for impulse [1]

Answer 62

force x time

Question 63

Describe a force time graph for a single footfall of a runner. [6]

Answer 63

graph negative- ground reaction force= foot push off ground 0- foot lifts off the ground more positive - acceleration max positive- max speed/steady pace starts going lower- deacceleration reaches 0- athlete stops

Question 64

What a force time graph look like if athlete is slowing down [2]

Answer 64

net impulse is negative | line is more below the graph

Question 65

What would the a. x axis b. y axis be labelled as on a force time graph [2]

Answer 65

time (s) force (N)