Biomechanical movement Flashcards
What is Newton’s law of inertia?
A force is required to change the state of motion.
The bigger the mass the larger the inertia of the object or body.
What is inertia?
Inertia is the resistance an object has to a change in its state of motion.
What is an example of Newton’s first law?
In the high jump, the athlete runs horizontally towards the bar and then changes their state of motion at take-off when they travel vertically to try to clear the bar.
What is Newton’s law of acceleration?
The magnitude (size) and direction of the force applied to a body determine the magnitude and direction of the acceleration given to a body.
Force = mass x acceleration
What is an example of Newton’s second law?
To provide acceleration at the start of a sprint race, an athlete will have to apply a large force internally with their gluteals, quadriceps and gastrocnemius as they drive forward.
A tennis player will impart a large force on the ball, so it accelerates over the net in the direction in which the force is applied.
What is Newton’s law of action and reaction?
Every action (force) has an equal and opposite reaction (force).
Action acts on one of the bodies, and the reaction to this action acts on the other body.
Most applications involve Ground Reaction Force.
What is an example of Newton’s third law?
At a sprint start, the athlete pushes back on the blocks as hard as possible (action), and the block push forwards on the athlete (reaction) and provides forwards acceleration on the athlete.
What is ground reaction force?
The force exerted on the ground by the body in contact with it.
An individual standing still on the ground exerts a contact force (the weight of the individual) and at the same time an equal and opposite ground reaction force is exerted by the ground on the individual.
What is a scalar quantity?
When measurements are described in terms of just their size or magnitude, not direction.
Speed, distance, mass and temperature.
What is speed?
The rate of change of position.
Speed (m/s) = distance covered (m) / time taken (s)
What is centre of mass?
The point of concentration of mass.
For someone standing, it is between the hip region and differs by gender.
Males have more weight concentrated on their shoulders and upper body, so have a slightly higher centre of mass.
What factors affect stability?
The height of centre of mass - lowering it increases stability.
Position of line of gravity - should be central over the base of support to increase stability.
Area of the support base - the more contact points, the larger the base and the more stable.
Mass of performer - the greater the mass, the more stability, due to increased inertia.
What are levers?
It consists of a fulcrum (pivot), weight to be moved (resistance) and source of energy (effort).
The joints are fulcrums, the effort is provided by muscles, and the resistance is the weight of the body part that is being moved against the force of gravity.
What are first class levers?
The fulcrum is located between the effort and the resistance.
In the body, this is the movement of the head and neck during flexion and extension, and the extension of the elbow.
What are second class levers?
The resistance lies between the fulcrum and the effort.
The only example in the body is plantarflexion of the ankle.
What are third class levers?
The effort lies between the fulcrum and the resistance.
This is found in all other joints of the body.
What is mechanical advantage and disadvantage?
This depends on the force arm and the resistance arm.
The force arm is the shortest perpendicular distance between the fulcrum and the application of effort.
The resistance arm is the shortest perpendicular distance between the fulcrum and the resistance.
What is mechanical disadvantage?
When the resistance arm is greater than the effort arm.
This means the lever system cannot move as heavy a load but can do it faster.
It also has a larger range of movement.
What is mechanical advantage?
When the effort arm is longer than the resistance arm.
The lever system can move a large load over a short distance and requires little force.
It has a small range of movement, and it is difficult to generate speed and distance.
What is the mechanical (dis)advantage of the levers?
Second class can generate large forces, but is slow and low RoM.
First and third have large RoM and can move quickly but cannot apply much force to move heavy objects.