Biomechanics

Question 1

What are the features of 1st class levers?

Answer 1

• Fulcrum is in the middle of the lever.
• Examples are movement of the neck and extension of the elbow.
• Sporting example is a header in football.

Question 2

What are the features of 2nd class levers?

Answer 2

• Load is in the middle.
• Plantar flexion of the ankle.

Question 3

What are the features of third class levers?

Answer 3

• Effort is in the middle.
• All the other joints/ movements in the body.
• Examples are: hip, knee, elbow flexion.

Question 4

What is mechanical disadvantage?

Answer 4

• Mechanical disadvantage is when the load arm is greater than the effort arm.
• Has a large range of movement, can’t move heavy loads, but can move loads at a quick pace.
• Third class levers always have a mechanical disadvantage.

Question 5

What is mechanical advantage?

Answer 5

• Mechanical advantage is when the effort arm is longer than the load arm.
• Can move a large load over a short distance, with little force, but has a small range of movement and difficult to generate speed and distances.
• Second class levers always have a mechanical advantage.

Question 6

What are the 4 factors that affect stability?

Answer 6

• Centre of mass (height of it)
• Line of gravity (position of it)
• Base of support (Area)
• Mass (of the performer)

Question 7

What is stability?

Answer 7

The body’s resistance to movement.

Question 8

What is balance?

Answer 8

The ability to maintain the line of gravity of the body within the base of support, with minimal posture sway.

Question 9

How does the centre of gravity/mass affect stability?

Answer 9

• Centre if an objects mass, point around which the mass of the object is equally balanced.
• Lowering the height of the centre of mass will increase stability.

Question 10

How does the line of gravity affect stability?

Answer 10

• Helps you determine balance.
• Represented by drawing a straight line from the centre of gravity/ mass to the ground.
• Should be central over the base of support to maximise stability.

Question 11

How does the base of support affect stability?

Answer 11

• Area within an outline of all contact points.
• The more contact points (larger area) the larger the base of support is and the greater the stability.

Question 12

What is a scalar quantity?

Answer 12

A quantity which only has a magnitude (size). e.g distance and speed.

Question 13

What is a vector quantity?

Answer 13

A quantity which has both a magnitude and a direction. (e.g velocity)

Question 14

What is linear motion?

Answer 14

Motion in a straight line, with all body parts moving the same distance at the same speed in the same direction.

Question 15

What is Newtons 1st Law (inertia)?

Answer 15

• Inertia is the resistance an object has to a change in its state of motion.
• If an object is at rest, it will remain at rest. Similarly, if it is moving in one direction it will continue to do so at the same velocity until another force is exerted upon it.
• A force is required to change the state of motion.

Question 16

What is Newtons 2nd law (acceleration)?

Answer 16

• The acceleration of a body is directly proportional to the force of the body causing it.
• Force= mass X acceleration.
• The rate of acceleration is directly proportional to the force causing the change.
• The size and direction of a force applied to a body determines the size and direction of the acceleration given to a body.
• Only if mass remains constant.

Question 17

What is Newtons 3rd Law (reaction/action)?

Answer 17

• To every action (force) there is an opposite and equal reaction (force).
• GRF is the force exerted on the ground by the body in contact with it.
• A person standing still (weight), equal force will act equally but opposite, therefore they will remain stationary.