Biomechanical Movement

Question 1

What is Angular motion?

Answer 1

• Angular rotation refers to rotation
• Rotation is movement around a fixed point/axis
• Can involve the whole body or just an arm or leg
• In a runner, they run in a straight line but have large amounts of rotation in their arms and legs.

Question 2

What is an eccentric force?

Answer 2

An off-centre force,

Question 3

When does Angular motion occur?

Answer 3

Angular motion occurs when a force is applied outside the centre of mass.

Question 4

What is the transverse axis?

Answer 4

• The transverse axis runs from side to side across the body.
• A somersault rotates a body in a transverse axis.

Question 5

What is the Sagittal axis?

Answer 5

• The Sagittal axis runs from front to back.
• A cartwheel rotates around the sagittal axis.

Question 6

What is the Longitudinal axis?

Answer 6

• The longitudinal axis runs from top to bottom.
• A multiple spin in ice skating rotates in a longitudinal axis.

Question 7

What is torque?

Answer 7

Often called the moment, torque is the turning force and causes angular motion to occur.

Question 8

Torque causes an object to turn about it’s axis of rotation. It is dependent on 2 things:

Answer 8

1) The greater the size of the force, the greater the torque.
2) Application of the same force further away from the axis, will increase torque.

Question 9

How do you calculate ‘moment of force’?

Answer 9

Moment of force/torque (Nm)= Force (N) X Perpendicular distance from the fulcrum (M)

Question 10

What are the 2 things ‘moment of force’ can be?

Answer 10

• Resistance arm
• Effort arm

Question 11

What is the resistance arm?

Answer 11

Shortest perpendicular distance between fulcrum and resistance.

Question 12

What is the effort arm?

Answer 12

Shortest perpendicular distance between fulcrum and effort.

Question 13

What is the definition of speed?

Answer 13

Speed can be defined as the rate of change of a position and can be calculated as: speed (m/s)= distance covered (m)/ time taken (s)

Question 14

What type of quantity is speed?

Answer 14

Scalar quantity

Question 15

What is velocity?

Answer 15

Velocity refers to how fast a body travels in a certain direction. It is the rate of change of displacement: velocity= displacement (m)/ time (s)

Question 16

What type of quantity is velocity?

Answer 16

Vector quantity.

Question 17

What is the equation to calculate average acceleration?

Answer 17

Average acceleration (ms-2)= change in velocity/ time

Question 18

When is momentum conserved?

Answer 18

Momentum being conserved occurs when a performer or object is in flight. When in flight neither mass nor velocity can be altered. Mass is constant. Velocity can only be altered by external forces (air resistance + gravity).

Question 19

What is angular velocity?

Answer 19

Refers to the rational speed of an object and the axis about which the object is rotating. It’s a vector, it has direction as it refers to angular displacement covered in a certain time.

Question 20

What is the equation to find angular velocity?

Answer 20

Angular velocity (rad/s)= Angular displacement (rad)/ time taken (s).

Question 21

What is angular acceleration and how is it calculated?

Answer 21

The rate of change of angular velocity. Angular acceleration p= (rad/s2)= Change in angular velocity (rad/s)/ time taken (s).

Question 22

What is Newton’s second law in relation to angular motion?

Answer 22

‘The rate of change of angular momentum (acceleration) a body is proportional to the force (torque) causing it and the change that takes place in the direction which the force (torque) acts.

Question 23

What is Newton’s third law in relation to angular motion?

Answer 23

‘When a force (torque) is applied by one body to another, the second body will exert an equal and opposite force (torque) on the other body?

Question 24

What are the 2 factors that the moment of inertia acting on a lever is dependant on?

Answer 24

1. The mass of the object.
2. How the mass is distributed from the point of rotation. The further the mass from the point of rotation, the bigger the moment of inertia and the harder to stop/start movement.

Question 25

How does the mass of an object affect the moment of inertia?

Answer 25

The greater the mass, the greater the resistance to change and therefore the greater the moment of inertia. For example, a ten pin bowling ball is harder to roll along the ground than a football, but once rolling, it is more difficult to stop. Same with rotation.

Question 26

How does the distribution of mass from axis of rotation affect the moment of inertia?

Answer 26

Closer the mass to the axis of rotation, the smaller the inertia. Thus, the easier it is to rotate. Increasing the distance of the distribution of mass from the axis of rotation will increase moment of inertia, but more rotation slower.

Question 27

What is the equation to calculate angular momentum?

Answer 27

Angular velocity X moment of inertia

These two are inversely proportional, angular momentum is concise red so if moment of inertia increases, angular velocity decreases, visa versa.

Question 28

What is the conservation of angular momentum law?

Answer 28

A body will keep on sprinting or rotating unless forces act upon it. A body is unlikely to lose mass during movement, but can change it’s distribution or distance from the axis of rotation.

Question 29

What is equilibrium when when is it achieved?

Answer 29

For a body to be in equilibrium (balance) the sum of the clockwise moments is equal to the sum of the anti-clockwise moments about the fulcrum. The resistance arm must equal the effort arm.

Question 30

What is Newton’s first law in terms of angular motion?

Answer 30

‘Every body continues in its state of rest or will turn about its axis of rotation unless compelled to change that state by an eternal rotational force (torque) acting upon it.’