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1.3.a Biomechanical Principles, Levers and the Use of Technology > exam qs > Flashcards

exam qs Flashcards

1
Q

Apply Newton’s third law of motion to a footballer heading a ball. (3)

A
  • Footballer applies a (action) force on the ball
  • Ball applies a reaction force to / on the head
  • (Reaction force) is equal (in size) to the (action) force from the head
  • (Reaction force) is in opposite direction to (action) force
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2
Q

A rugby player with a mass of 90kg accelerates at a rate of 2m/s/s (2ms–2).
Calculate the force the rugby player has generated to achieve this rate of acceleration.
Show your workings (2)

A
  • Force = mass x acceleration OR 90 x 2
  • 180 Newtons / N
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3
Q

Define the term ‘centre of mass’. (1)

A
  • The point at which the body is balanced (in all directions)
  • The point from which weight appears to act
  • The point around which a body may rotate
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4
Q

(ii) Explain, using sporting examples, the relationship between centre of mass and stability (5)

A
  • Stability is maintained if CoM is over base of support, e.g. swimmer on starting blocks
  • The larger the base of support the greater the stability, e.g. wrestler widening points of contact on floor
  • The lower the CoM the greater the stability, e.g. rugby player lowers CoM when going into tackle to maintain balance
  • The closer the line of gravity (vertically downwards from CoM) to edge of base of support the less stable, e.g. ‘Set’ in sprinting athlete moves CoM forward reducing stability for a quick start.
  • Sports performers, e.g. gymnasts move their CoM to middle of base of support to increase stability in a handstand
  • Sports performers, e.g. trampolinists move their CoM outside base of support so they are unstable allowing rotation / somersaults
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5
Q

Describe the lever system at the elbow during the upward phase of a biceps curl. (3)

A

Three marks from:
- Third class lever
- fulcrum – effort - load OR LEF / FEL (accept labelled diagram)
- Fulcrum is elbow joint
- Effort is contraction of biceps (brachii)
- Load is weight/resistance (and (weight of) forearm)
- Lever arm is forearm (and hand)

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6
Q

Evaluate the effectiveness of the lever system at the elbow during the upward phase of a
biceps curl. (2)

A

Two marks from:
- Mechanical disadvantage
- Large effort is needed to move a small load
- Can move loads at high velocity / speed / acceleration

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7
Q

Evaluate the use of limb kinematics to enhance performance in sport (4)

A

Four marks from:
- Video / motion / 3D analysis of sporting action
- Joint / limb / angle / velocity / acceleration / gait / movement efficiency evaluated
- (+ve) Accurate / objective / immediate data produced
- (+ve) To enhance / adjust technique
- (-ve) Requires specialist training / correct placement of markers
- (-ve) Expensive OR laboratory conditions

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8
Q

A basketball player jumps upwards from one foot to reach a rebound.
Draw a free body diagram to show the vertical forces acting at take off and explain the resulting motion of the basketball player + explain (5)

A
  • Weight force acting vertically downwards from C of M
  • Reaction force/Normal reaction acting vertically upwards from the point of
    contact with the ground and longer than weight force
    Explanation:
  • (R>W) R>W/ Reaction force is greater than weight
  • (Net force) (Positive) net force
    Or (external) unbalanced force
  • (Acceleration) There is acceleration (upwards)
  • (Take off) The basketball player leaves the ground
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9
Q

A rugby player of mass 96 kg takes 2.5 seconds to accelerate from a standing start to 8 m / s.
Calculate the weight of the player, their acceleration between 0 s and 2.5s and their momentum at maximum velocity. (Assume g = 10 m / s2)
- Weight of rugby player:
- Acceleration between 0 s and 2.5 s:
- Momentum at maximum velocity:
(5)

A
  • Weight = mass x acceleration due to gravity / W = mg or W = 96 x 10
    = 960N or 960Newtons or 960kgm/s2
  • acceleration = Final velocity – initial velocity divided by time or v-u/t or
    change in velocity over time
    or 8 – 0 /2.5
    = 3.2m/s/s or 3.2 m/s2 or 3.2 ms-2
  • Momentum = mv or mass x velocity or 96 x 8
    = 768 kgm/s or 768 kgms-1
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10
Q

On the image shown in Fig. 8.1, use arrows to show four types of force acting on the cyclist while they pedal forwards.
The arrows must show the point of application, the direction of the forces and the magnitude of the forces

A
  • Weight / W – vertically down from CoM
  • Reaction / R – vertically up from ground on both wheels which equal
    weight
  • Air resistance / AR – backwards from CoM
  • Friction / F – forwards from ground on both wheels
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11
Q

State the metric units of measurement for displacement and acceleration. (2)

A
  • (displacement) m / metres
  • (acceleration) metres/sec/sec OR ms-2 OR m/s2
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12
Q

Hockey players hit the ball at high speeds to prevent interceptions.
Apply Newton’s second law of motion to show how a hockey player may maximise the ball’s acceleration. (3)

A
  • Acceleration is proportional to the size of force applied/ Force = mass x acceleration/ F = ma
  • (Force)The hockey player applies a large force to increase acceleration
  • (Velocity)Size of force is dependent on velocity/speed of stick (as it contacts ball)
  • Player will attempt to maximise velocity/speed of stick/ power of the hit
  • Size of force is also dependent on mass of stick
  • Player may use a heavier stick to increase force
  • Heavier stick will increase/maximise acceleration as long as velocity/speed of stick is not lost/reduced/player can swing heavy stick as quickly as a lighter one
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13
Q

Calculate the force applied to a hockey ball with a mass of 0.16kg to cause it to accelerate at a rate of 30ms−2. Show your workings. (2)

A
  • Force = mass x acceleration / m x a / 0.16 x 30
    = 4.8 Newtons/N
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14
Q

Identify all the component parts of a lever system. Use a practical example from sport to show the component order of a first class lever. (4)

A
  • Fulcrum, effort and load
  • Effort arm and load arm
  • 1st class = Effort – fulcrum – load or load – fulcrum – effort
  • E.g. movement of head to perform a header in football or elbow extension to throw a ball
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15
Q

Explain, using practical examples, how force plates are used to enhance sporting performance. (5)

A
  • To analyse gait/walking/running e.g. improve technique of marathon runner
  • To analyse posture of e.g. improve persistent back pain of rugby player
  • To measure/improve balance of e.g. to improve performance of swimmer on starting blocks
  • For rehabilitation from injuries e.g. to enhance recovery of a footballer after an ankle sprain
  • To measure force/power/acceleration e.g. to improve technique at take-off for a high jumper
  • To optimise angle of take-off for e.g. to improve technique of a long jumper
  • Prevention of injury on landing e.g. to improve a cricket fast bowler in delivery stride
  • To adapt/design prostheses for e.g. to enhance performance of a paralympic 100m sprinter
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16
Q

Give a sporting example for the following classes of lever: 2nd class, 3rd class (2)

A
  • (second class) e.g. calf raise or take-off phase of high jump at ankle
  • (third class) e.g. bicep curl or knee extension when kicking a ball
17
Q

Identify a technology that is used in performance analysis to:
improve streamlining of an object,
evaluate human movement in three dimensions (2)

A
  • wind tunnels
  • limb kinematics
18
Q

Identify the vertical forces acting on the gymnast and explain their relationship during the
handstand. (3)

A
  • (identify) weight and reaction (force)/ W and R (forces)
  • (handstand) W = R
  • (Forces) Forces are equal (in size) and opposite (in direction) or net force = 0 or forces are balanced or forces cancel each other out
19
Q

Describe how limb kinematics can be used to enhance performance in sport (2)

A
  • Video/ motion/ 3D analysis of a sporting action/ movement/ skill/ technique
  • Assesses gait/ movement efficiency/ velocity/ acceleration/ joint angles
  • (technique) (Identifies small changes) to improve technique
  • Helps prevent (repetitive strain/joint) injuries
20
Q

Define Newton’s third law of motion and apply it to a sporting example of your choice. (3)

A
  • For every action/ force (applied to a body) there is an equal and opposite
    reaction (force)
  • E.g. a shot putter applies a force to a shot
  • E.g. the shot applies an equal/ same and opposite reaction/ force to the shot
    putter
21
Q

Using practical examples, explain how the elbow joint can act as a fulcrum for two different lever systems (4)

A
  • First class lever (for extension) e.g. triceps extensions/ throwing an object/ tennis serve
  • First class lever fulcrum in the middle/ EFL/ LFE/ appropriate diagram
  • Third class lever (for flexion) e.g. biceps curls (up or downward phase)/ bowls
  • Third class lever effort in the middle/ FEL/ LEF/ appropriate diagram
22
Q

Compare what is meant by ‘balanced forces’ and ‘unbalanced forces’ and explain what is meant by the term ‘net force’. (5)

A

Balanced:
- Two (or more)(opposing) forces are
equal (in size)
- No change in motion
- Constant velocity/rest occurs
Unbalanced:
- Two (or more)(opposing) forces are not equal (in size)
- Change in motion
- Acceleration/deceleration occurs
Net force:
- The sum of all forces/resultant force acting on a body
- (Net force) zero if forces are balanced
- (Net force) positive/negative if forces are unbalanced / a net force shows the
direction and magnitude of acceleration / deceleration / change in motion

23
Q

Define ‘acceleration’ and describe three ways in which a performer can increase their acceleration during sport or physical activity. (4)

A
  • Acceleration = rate of change of velocity or (final velocity – initial velocity) ÷ time taken
  • (Increase force/velocity/speed) e.g. a sprinter can apply a greater force to the
    blocks/track
  • (Increase friction) e.g. a long jumper can wear spikes to increase friction with the ground
  • (Reduce mass/weight) e.g. a high jumper loses weight prior to competition or high jumper can move their mass at a greater velocity
  • (Improve technique) e.g. a runner adjusts technique/body position so that more force is generated in a forward/horizontal direction
  • (Reduce air resistance) e.g. a sprint cyclist adopts a streamlined shape to minimise air resistance / more aerodynamic
24
Q

Calculate, to one decimal place, the average speed of a speed skater who covers a distance of 400 metres in 27 seconds. (1)

A

(Average) speed = (distance/time taken = 400 ÷ 27) = 14.8 metres/second / m/s / ms

25
Q

Define Newton’s first law of motion (1)

A

A body continues in a state of rest or uniform velocity unless acted on by
an external/unbalanced force

26
Q

Explain why Newton’s first law applies to a golf ball in the following situations:
A golf ball on the tee, A golf ball in flight at maximum velocity (3)

A
  • (On tee) The ball will remain at rest on the tee / ball has balanced forces applied
  • (On tee) Until it is struck by the golf club / an unbalanced force is applied
  • (In air) Ball is at maximum velocity as struck/ external or unbalanced force is applied
  • (in air) … the forces become unbalanced/ W/gravitational pull/ air resistance act on ball/change its velocity
27
Q

Explain, using a sporting example, why Newton’s third law of motion is also known as the law of reaction. (2)

A
  • For every action (force) applied to a body there is an equal and opposite
    reaction force
  • E.g. A footballer applies a force from their foot to the ball and the ball applies an equal and opposite force back to the foot
28
Q

Outline one sporting situation where a wind tunnel is used to enhance performance, two
benefits of this technology and one disadvantage. (4)

A
  • (Sporting example) e.g. cyclist or F1 car or speed skater or downhill skier
  • improve technique/ reduce drag/ air resistance or optimise body position of
    cyclist/skater/skier
  • Increase streamlining/aerodynamic design or improve flow of air around a body or increase lift/ downforce / improve design
  • External factors can be controlled (by scientists)/ variable can be explored
  • Specialised facilities or expensive or not available to all
  • Data requires complex analysis / qualified professionals

1.3.a Biomechanical Principles, Levers and the Use of Technology (4 decks)

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