biomechanics

Question 1

newtons 1st law

Answer 1

• “A body continues in its state of rest or state of motion unless acted upon by an external force” Also referred to as law of inertia

Question 2

newtons 2nd law

Answer 2

The acceleration of a body is proportional to the force applied to it and inversely proportional to the mass of the object” also referred to the law of acceleration

Question 3

newtons 3rd law

Answer 3

• For every action there is an equal and opposite reaction.

Question 4

internal force

Answer 4

• Structures of the body that interact to produce movement

- E.g. action of muscles and tendons that act together to produce forces that cause movement.

Question 5

external force

Answer 5

• Result from the interaction between the body and the environment. These can include contact forces and non-contact forces.
• E.g. gravity, friction, air resistance, water resistance

Question 6

linear motion

Answer 6

• Where movement is along a straight line, there is no rotation, and all body parts move in the same direction at the same speed.
• E.g. an ice skater gliding after they completed a movement or a cyclist who stops pedalling.

Question 7

rectilinear motion

Answer 7

• Movement is linear and occurs through a straight line

- E.g. a basketball chest pass or baseball pitch where the balls path is flat and in a straight line

Question 8

curvilinear motion

Answer 8

• Movement is linear but object moves through a curved trajectory
• E.g. the pathway of a ball during a shot in netball or the flight path of a long-distance ski jumper

Question 9

angular motion

Answer 9

• Where all parts of a body move through a rotational pathway, through the same angle, in the same direction and at the same time.
• E.g. when a gymnast performs a giant circle on a bar, the entire body rotates, with the axis of rotation passing through the centre of the bar

Question 10

general motion

Answer 10

• Combination of linear and angular motion

- E.g. a cyclist may move in a straight line as a result of the rotation of the legs about the hip joint

Question 11

distance

Answer 11

• Refers to how far you have travelled from your start to finish point
• Measured in terms of total distance covered

Question 12

displacement

Answer 12

• Measures the overall change in position

Question 13

speed

Answer 13

• Measure of the distance an object travels per unit of time
• Representative of how quickly you cover a given distance
• Calculated by dividing distance travelled by time taken

Question 14

velocity

Answer 14

• Speed in a given direction
• Calculated by dividing displacement by time taken
• A change in velocity could be representative of a change in speed, change in direction, or both

Question 15

acceleration

Answer 15

• Rate at which the velocity of a body changes with respect to time
• Positive acceleration: velocity is increasing
• Negative acceleration: velocity decreasing

Question 16

internal rotation

Answer 16

• Uses joints around which the rotational movement occurs

Question 17

external rotation

Answer 17

• Occurs when body parts rotate around a point that occurs outside the body

Question 18

static balance

Answer 18

• The ability to hold a stationary position

- For example, completing a handstand, pyramid in cheerleading, swimmer/runner on the blocks at the start of a race

Question 19

dynamic balance

Answer 19

• The ability to hold a moving position to execute an outcome
• For example, catching a wave while surfing, riding a skateboard, kicking a ball in soccer

Question 20

centre of gravity

Answer 20

• Gravity acts on the body in a vertically downward direction, towards the centre of the earth through a point in the body
• The theoretical point in an object, located either inside or outside of the body, where all of the body’s mass is equally distributed
• As your position changes so does your centre of gravity

Question 21

line of gravity

Answer 21

• An imaginary vertical line passing downwards throughout the centre of gravity to the ground or surface the person is on
• The closer the line of gravity is to the limits of the base support, the less the degree of stability of the object
• Movement is easier when the line of gravity falls outside the objects base of support

Question 22

base of support

Answer 22

• Area bound by the outermost regions of contact between a body and support surface
• It refers to the area beneath an object or person that includes every point of contact that the object or person makes with the supporting surface
• These points may be a chair the person is sitting on or even feet on the ground/own body

Question 23

balance and stability are affected by?

Answer 23

• Mass of the object – the greater the mass of an object the greater the stability
• Size of the base of support – the greater area of support the greater the stability
• Height of the centre of gravity above base of support – the lower the greater the stability
• Position of line of gravity relative to base of support -
• Increasing BOS in direction of oncoming force
• Positioning COG near edge of BOS in direction of oncoming force

Question 24

force

Answer 24

• The concept of force is common to all newtons laws
• Force is the pushing or pulling effect of a body on another body that can:
• Get objects moving
• Stop objects moving
• Change the direction of a moving object
• Change the speed of a moving object
• Balance another force to keep an object still

Question 25

internal force

Answer 25

• Structure of the body that interact to produce movement

- E.g. action of muscles and tendons that act together to produce forces that cause movement

Question 26

external force

Answer 26

• Result from the interaction between the body and the environment. These can include contact and non-contact forces
• E.g. gravity, friction, air resistance, water resistance

Question 27

contact forces

Answer 27

• the forces that act on objects that come into direct contact with one another.
• E.g. frictional forces, ground forces, air resistance, water resistance

Question 28

non-contact forces

Answer 28

the forces that act on the objects without coming into direct contact with one another. E.g. gravity

Question 29

inertia

Answer 29

• Describes the amount of resistance to a change in an objects state of motion
• Is directly proportional to an objects mass
• Thus the greater the mass of the object, the greater its inertia, and the greater, the force required to initiate its movement or change its state of motion

Question 30

momentum

Answer 30

• A measure of the amount of motion possessed by a moving body it is the product of mass and velocity
• An object can only have momentum if it is moving
• The greater its momentum, the more force that needs to be applied to either stop or slow the object down
• As a result when two bodies collide, the one with the most momentum will be least affected

Question 31

impulse

Answer 31

• The application of force over a period of time to change the momentum of an object