Bio Mechanics

Question 1

Define the terms force, speed, velocity, displacement, acceleration, momentum and impulse

Answer 1

Force: a push or pull upon an object resulting from the object’s interaction with another object

Speed: the rate at which an object covers a distance

Velocity: is a change in displacement divided by the time taken for the change to take place. It has size (how fast) and direction.

Displacement: the difference between an object’s final position and starting position

Acceleration: the rate at which an object changes its velocity

Momentum: the quantity of motion of a moving body, measured as a product of its mass and velocity

Impulse: is force x time, and is what is needed to change a bodys momentum

Question 2

Define the term “center of mass”

Answer 2

Point at which the mass and weight of an object are balanced in all directions

Question 3

Explain that a change in body position during sporting activities can change the position of the centre of mass [with an example]

Answer 3

Gymnast doing the Fosbury Flop:
- Center of mass is no longer within the body

Question 4

Distinguish between first, second and third class levers [with examples]

Answer 4

First: RFE [crowbar and rock]

Second: FRE [wheelbarrow]

Third: FER [golf club]

Question 5

Label anatomical representations of levers

Answer 5

First: Triceps

Second: Ankle

Third: Bicep

Question 6

Define Newton’s three laws of motion

Answer 6

1: Inertia [an object will not change its motion unless a force acts on it]

2: Acceleration [the force on an object is equal to its mass times its acceleration]

3: Action / Reaction [when two objects interact, they apply forces to each other of equal magnitude and opposite direction]

Question 7

Explain how Newton’s three laws of motion apply to sporting activities

Answer 7

Newton’s second and third laws enable an athlete to accelerate out of starting blocks. Impulse momentum relationship. The law of conservation of momentum should also be considered.

Question 8

State the relationship between angular momentum, moment of inertia and angular velocity.

Question 9

Explain the concept of angular momentum in relation to sporting activities.

Question 10

Explain the factors that affect projectile motion at take-off or release

Question 11

Outline the Bernoulli principle with respect to projectile motion in sporting activities.

Answer 11

• The relationship between air flow velocity and air pressure is an inverse one, and is expressed in Bernoulli’s principle
• The pressure difference causes the spinning golf ball to experience a force directed from region of high air pressure to low
• A golf ball with backspin will experience higher air pressure on the bottom of the ball and lower air pressure on the top of the ball, causing a lift force
• The lift force is perpendicular to the direction of the air flow.

*Still photography and video can be used to record and analyse movement. A visit to a university may be possible to see the use of high-speed photography, photoelectric cells and motion analysis software.