Biomechanics Flashcards
What is force ?
A push or pull that alters or tends to alter the state of motion of a body
Can cause body at rest to move
Can cause moving body to:
- change direction
- accelerate
- decelerate
- change objects shape
What is Newtown’s 1st law of motion ?
Law of inertia
Object that’s in motion will remain in motion at constant velocity or an object that is stationary will remain stationary until acted on by external force
Inertia: the reluctance of an object to change its state of motion
What’s newtons 2nd law of motion ?
Law of acceleration
Acceleration is directly proportional to force
Acceleration is indirectly proportional to mass
Force = mass x acceleration
What’s newtons 3rd law of motion ?
Law of action - reaction
For every action there’s an equal and opposite reaction
One object exert force on object 2 and object 2 will exert equal and opposite force back onto object 1
What are the equations for speed, distance and time ?
Distance = speed x time
Speed = distance / time
Time = distance / speed
What is momentum ?
Quantity of motion
Units are Kg - m/s
Momentum = mass x velocity
What’s velocity ?
The speed something is moving in a given direction
What’s impulse ?
- The product of the amount of force and how long the force is applied for on an object
- Impulse = force x time
- Impulse = change in momentum
- Impulse can be positive or negative
- impulse can decrease over time due to reduction of force output
What’s positive impulse ?
Occur when force is applied in same direction as the motion of an object
Increasing velocity therefore increasing momentum
What’s negative impulse ?
Occur when force is applied in opposite direction to the motion of an object
Decreasing velocity therefore decreasing momentum
What’s net impulse ?
Overall change in momentum of an object
Net impulse = positive impulse - negative impulse
How do you increase impulse ?
Increase force applied to object
Increase time force is applied
Then combine them
What’s balance ?
Maintain centre of mass over base of support
What’s stability ?
Ability of body to return to equilibrium after being displaced
What’s centre of mass/gravity ?
Point at which body is balanced in all directions
Point in an object where weight acts
What’s line of gravity ?
Imaginary line which passes vertically from centre of mass to ground below an object
What are the four factors that affect stability ?
Mass of an object
Height of centre of mass
Size of base of support
Points of contact
How does mass of an object affect stability ?
Greater the mass the more stable due to high inertia
More forces is needed to displace object
How does size of base of support affect stability ?
Large BOS = greater stability
Helps maintain centre of mass within bass of support
Harder to knock centre of mass out of base of support
How does height of centre of mass affect stability ?
Lower the centre of mass = greater the stability
More difficulty for COM to leave BOS due to less leverage
How does points of contact affect stability ?
More POC and increase size of POC = greater stability
Due to more evenly distributed mass and increase friction with surface
What are the three components of a lever ?
Fulcrum (fixed point or pivot)
Effort (point where force is applied)
Load (point where weight is coming from)
What are the functions of levers ?
Increase speed and range of motion
Generates max force against resistance
