Biomechanics Flashcards
What are Newton’s three laws in order?
- Inertia
- Acceleration
- Action and reaction
Describe the law inertia.
objects in motion to stay in motion and objects at rest to stay at rest, unless a force causes its speed or direction to change. (Eg. When the bus stops suddenly, people fall forward)
Describe the law of acceleration
When a force acts on an object, the acceleration that takes place depends on the amount of force applied. (Eg. hitting the gas or the brakes)
Describe the law of action and reaction
For every action, there is an equal and opposite reaction, This means that when an object exerts a force on a second object, the second object must also exert an equal-sized force back onto the first object in the opposite direction. (Eg. when you push on a box, the box pushes back on you.)
What are the three types of motion?
Linear, angular and general motion.
What is force?
Forces can be internal, the force created by muscular contractions. Forces can be external, also know as resistive forces.
What forces may impact on an object?
-Friction
-Fluid resistance
-Drag
-Gravity
What is friction?
Is the force that opposes movement when two surfaces move across each other (wax on a surfboard).
Linear motion
Object and its mass move in the same direction, in a straight line.
Angular motion
When the body or an object turns about an axis of rotation.
General motion
A combination of both linear & angular motion. (Riding a bike, the bike moves in a linear direction but the pedals move in angular motion around an axis).
Principles of motion
-Linear motion
-Angular motion
-General motion
-Magnus Effect
Difference between speed and velocity?
Speed refers to an object’s change in distance with respect to time, whereas velocity refers to an object’s change in displacement with respect to time.
What is momentum?
Momentum is the product of the mass and velocity of an object.
What is force summation?
The combination of forces produced by different parts of the human body.
What is projectile motion?
The movement of an object through the air is known as projectile motion. The path of a projectile is called its trajectory. (Eg. bullet shot from a gun)
What four factors affect projectile motion?
-Angle of release
-Height of release
-Speed of release
-Air resistance
What is the magnus effect?
The Magnus effect explains the
deviation of flight paths of balls
with spin. A spinning object moving through a fluid moves away from its straight path because of pressure differences that develop in the air.
What is topspin?
Tends to shorten the flight of the ball, which dips sharply at the end of its flight. (Eg. A tennis serve)
What is backspin?
Tends to shortens the flight of the ball, which falls more slowly at the end of the flight. (Eg. Drop punt in footy)
What is sidespin?
Makes the ball curve left or right in the direction of the spin. (Eg. Baseball curveball.)
What is force summation influenced by?
-number of body parts used
-order and timing of the movement
-force and velocity generated
-way in which the body is stabilised and balanced
What is balance?
Balance refers to the ability to control the body when you are not moving.
What is stability?
Stability refers to the ability to control the body when you are moving.
What are the four factors affecting balance and stability?
-the mass
-the base of support
-the centre of gravity
-the line of gravity
Base of support
The base of support is the area around the outside edge of your body in contact with the ground/surface
Centre of gravity
The centre of gravity is the average location of the weight of an object.
Line of gravity
An imaginary vertical line from the centre of gravity to the ground.
Displacement
Change in position, from a to b.
