newtons laws and biomechanical principles

Question 1

newtons first law of motion (law of inertia)

Answer 1

• every body continues in its state of rest or motion in a straight line, unless compelled to change that state by external forces exerted upon it
• inertia
• the resistance an object has to change in its state of motion
• if an object is at rest , it will remain still
• if the object is moving in one direction it will continuoe to do so at the same velocoity until another force is exerted upon it
• E.G - a football will stay on the penalty spot until a force is applied on it - a foot
• this will continue until stopped by the net (an unbalanced force)

Question 2

newtons second law of motion (the law of acceleration)

Answer 2

• the rate of momentum of a body (or the acceleration for a body of constant mass) is proportional to the force causing it and he changed that takes place in the direction in which the force acts
• the magnitude and direction of the force dtermines the magnitude and direction of the acceleration for a body
  Force = mass x acceleration
• E.G a cricket ball being thrown compared to a shotput

Question 3

newtons third law of motion (the law of action/reaction)

Answer 3

• to every action (force), there is an equal and opposite reaction (force)
• action and reaction are equal and opposite and always occur in pairs
• action acts on one of the bodies and the reaction acts on the other body
• E.G a swimmer pushes back on the water with their hands and feet (action), at the same time the water thrusts the swimmer forward (reaction)

Question 4

football application of newtons law

Answer 4

• first law - In a penalty, the ball will remain on the spot unless it is kicked by the player
• second law - When the player kicks the ball during the game, the acceleration of the ball is proportional to the size of the force. The harder the ball is kicked, the further and faster it will go in the direction the force is applied.
• third law - When a footballer jumps (action) to win a header, a force is exerted on the ground in order to gain height. At the same time, the ground exerts an upward force (equal and opposite) reaction upon a player.

Question 5

centre of mass

biomechanical principles - centre of mass

Answer 5

• is the point of concentration of mass - or the point of balnce of a body
• the centre of mass will constantly change due to the body changing in a variety of sporting movements
• e.g raising your arms, your centre of mass would change in order to keep your body blanced
• if your lower your centre of mass it will increase your stability
• E.G a sprinter in the ‘set’ postition nd will have their centre of mass in their shoulders
• when they take their arms away they wil fall forward and create more speed and momentum

Question 6

males centre of mass

Answer 6

• have more weight concentrated in their shoulders and upper body

Question 7

female centre of mass

Answer 7

• have more weight concentrated in their lower body and hips

Question 8

factors affecting stability

Answer 8

• height of centre of mass
• lowering the centre of mass wil increase stability
• postion of the line of gravity
• it should be central over the base of support to increase stability
• mass of the performer
• often the greater the mass, the more stability there is because of interia
• area of support base
• the more contact points, the larger the base of suppor and increases stability
• E.G a headstand is more stable than a handstand because it has more contact points

Question 9

fulcrum

Lever system

Answer 9

• the part of the lever system that pivots
• joints are the fulcrum in the body
• triangle

Question 10

resistance

Lever system

Answer 10

• the load to be moved by a lever
• usally involves weight
• square

Question 11

effort

Lever system

Answer 11

• the force applied to move the resistance or weight ; in the body the effort is applied by the muscles exerting a force
• arrow

Question 12

FRE 123

Question 13

1st class lever system

Lever system

Answer 13

• the fulcrum is in the middle
• extension at the elbow joint
• tricep - effort
• hand/weight/ball - resistance
• elbow - fulcrum
• netall shot , throwing a football , lineup in rugby

Question 14

2nd class lever system

Lever system

Answer 14

• resistance is in the middle
• plantar flexion at the toes
• elbow - fulcrum
• gastronemeious - effort
• body weight - resistance
• gymnastics , diving , sprinting , defending the ball in netball

Question 15

3rd class lever

Lever system

Answer 15

• the effort is in the middle
• flexion and extension at the elbow (bicept curl)
• elbow - fulcrum
• hand - resistance
• bicep - effort
• bicept curl , RDLs (back)

Question 16

mechanical advantage

Lever system

Answer 16

• effort arm/resistance arm
• the effort arm is where the force is applied to the lever - arrow from effort to fulcrum
• the resistance arm moves the resitance (weight) - arrow from resistance to fulcrum
• want the resistance as close to the fulcrum (small resistance arm , big effort arm)
• first class levers can have a high mechanical advantage if the fulcrum is close to the resistance
• however they can have low mechanical advantage , if the fulcrum is closer to the effort you will have a low mechanical advantage

Question 17

high mechanical advantage

Lever system

Answer 17

• when a levers effort arm is longer than its resitance arm it has a higher mechanical advantage
• can move larger loads
• second class lever systms always have hih mechanical advantage

Question 18

low mechanical advantage

Lever system

Answer 18

• when a levers resitance arm is longer than the effort arm it has low mechanical advantage
• third class lever always has a low mechanical advantage