Biomechanics

Question 1

What is newton’s first law?

Answer 1

The law of inertia

Question 2

Give a definition of the law of inertia

Answer 2

A body continues in a state of rest or constant velocity unless acted upon by external or unbalanced forces.

Question 3

Apply N1 to an athlete in the blocks

Answer 3

The athlete will remain stationary in the blocks

Question 4

What is inertia?

Answer 4

The resistance of a body to change its state of movement, whether at rest or while moving

Question 5

What factors effect inertia?

Answer 5

-mass

Question 6

What is Newton’s second law?

Answer 6

The law of acceleration

Question 7

Describe the law of acceleration

Answer 7

A body’s rate of change of momentum is proportional to the size of the force applied, and acts in the same direction as the force applied.

Question 8

Apply N2 to a sprinter coming out the blocks

Answer 8

The greater the force applied to the sprinter, the greater the rate of change of momentum and therefore acceleration out of the blocks.

Question 9

What is Newton’s third law?

Answer 9

The law of reaction

Question 10

Give a definition for N3

Answer 10

For every action force applied to a body there is an equal and opposite reaction force.

Question 11

Give an example of how N3 can be applied to a high jumper

Answer 11

The more action force the high jumper applies in their takeoff jump the more reaction force the floor will apply back and the higher the jumper will leave the ground.

Question 12

Apply N3 to a batter in Cricket

Answer 12

The more force the batter applies to the ball the more force the ball will apply back and therefore travel further when hit.

Question 13

What is linear velocity and what is it measured in?

Answer 13

The rate of displacement, measured in m/s

Question 14

How do you calculate velocity?

Answer 14

Velocity = displacement/time

Question 15

What is acceleration and what are its units?

Answer 15

The rate of change in velocity, measured in m/s/s

Question 16

How do you calculate acceleration?

Answer 16

Acceleration = (final velocity-initial velocity)/time
or
Acceleration = force/mass

Question 17

What is force and what is it measured in?

Answer 17

Force is a push or pull that alters the state of motion of a body and is measured in Newtons

Question 18

How do you calculate force?

Answer 18

Force= mass x acceleration

Question 19

Define speed

Answer 19

The rate of change in distance over a given time

Question 20

Define linear velocity

Answer 20

The rate of change in distance over displacement

Question 21

What 5 things can forces do to a body?

Answer 21

• accelerate a body
• decelerate the body
• change shape of a body
• change direction
• create motion

Question 22

What factors affect air resistance?

Answer 22

• frontal cross-sectional area, the smaller the less ar
• shape, how air flows over the whole body
• velocity, greater v = more ar
• smoothness of body

Question 23

What is air resistance?

Answer 23

A form of fluid friction that opposes the motion of a body traveling through air

Question 24

What is friction?

Answer 24

the force that opposes the motion of two surfaces in contact

Question 25

What factors affect friction?

Answer 25

-roughness of ground, increase roughness=increase friction -roughness of contact surface, increase roughness= increase friction -temperature, increase temperature= increase friction -size of normal reaction force, which is equal and opposite to the weight of the athlete high mass athletes generate more reaction force therefore more friction

Question 26

What is linear motion?

Answer 26

movement in a straight or curved line where all parts move over the same distance, in the same direction at the same time

Question 27

Give examples of almost perfect linear motion

Answer 27

Water skiing skeleton bobsleigh ski jump on the way down

Question 28

what is angular velocity?

Answer 28

Angular displacement/ time

Question 29

What is angular velocity measured in?

Answer 29

radian/second

Question 30

What is moment of inertia?

Answer 30

resistance of a rotating body to change its state of angular motion or rotation

Question 31

How do you calculate moment of inertia and what is it measured in?

Answer 31

mass x distribution of mass from the axis of rotation | kgm2

Question 32

What is angular momentum?

Answer 32

The amount of momentum possessed by a rotating body

Question 33

What is angular momentum measured in and how do you calculate it?

Answer 33

kgm2rad/s | angular velocity x moment of inertia

Question 34

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

Answer 34

-mass of the body -Distribution of mass from the axis of rotation

Question 35

Describe the relationship between angular velocity and moment of inertia

Answer 35

If a body has a high moment of inertia it will have a lower angular velocity and if a body has a low moment of inertia it will have a higher angular velocity

Question 36

What is the angular analogue of Newton's first law?

Answer 36

A rotating body will continue to turn about its axis of rotation with constant angular momentum unless acted upon by an eccentric force or external torque

Question 37

Apply the angular analogue of newton's first law to a gymnast performing a somersault

Answer 37

The gymnast will have a constant angular momentum until she hits the floor however she changes her body position by redistributing her mass closer to the axis of rotation which decreases her moment of inertia therefore her angular velocity can increase

Question 38

Angular momentum cannot change throughout the movement, what is this termed as?

Answer 38

A conserved quantity

Question 39

Explain the conservation of angular momentum when a gymnast is in the take-off phase of a somersault

Answer 39

-Gymnast generates angular momentum through an eccentric reaction force from the floor through their body -They begin to rotate about the transverse axis - The distribution of their mass is away from the transverse axis so moment of inertia is high and angular velocity is low enabling them to control the movement

Question 40

Explain the conservation of angular momentum when a gymnast is in the flight phase of a somersault

Answer 40

- The gymnast distributes their mass close to the transverse axis as they tuck in their arms and legs - The moment of inertia decreases and the angular velocity increases so they can rotate more quickly - The angular momentum generated at take-off is conserved as there is no eccentric force

Question 41

Explain the conservation of angular momentum when a gymnast is in the landing phase of a somersault

Answer 41

- The gymnast distribute mass away from the transverse axis by untucking their arms and legs - This increases their moment of inertia and decreases the angular velocity so slows their speed of rotation down allowing them to have more control of their landing - As they land the floor applies an eccentric force to remove the conserved angular momentum, allowing the gymnast to stand at the end of the somersault

Question 42

What factors affect stability?

Answer 42

- height of centre of mass - size of base - position of line of gravity