Biomechanics
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Define Positive Work
Object displacement is in the same direction as the force applied.
Define Mechanical Work
Work is equal to: The amount of force applied to an object and the distance moved by the object.
What is the Formula for calculating Work?
Work = Force x Distance (F.s) (joules/Nm)
How do you calculate work if it is applied at an angle?
Work = Force x Cos {0} x distance (s) {0} = the angle between the force vector and the line of displacement
Define Negative Work
Object displacement is in the opposite direction to which the force is applied.
Define Net Work
Sum of positive and negative work Can be 0
What is an example of 0 work in the body?
Isometric muscle contractions e.g. muscle length remains unchanged like when you hold a weight with your arms outstretched
Define Power
The rate of doing work The amount of mechanical work done in a given time.
What is the equation for Power?
Work/ change in time Or Force x distance / Time
What is Power measured in?
Watts or Joules/Seconds
How can you use velocity with respect to Power and Force
Power = Force x Velocity
Define Inertia
Inertia is an objects resistance to change in its state of motion. Proportional to the body’s mass Scalar quantity Symbol – m, units – kg
Define Momentum
Momentum is the quantity of motion possessed by an object Remember velocity has a time component - so how fast something is going.
Describe the relationship between velocity and displacement in terms of graphical representation.
Velocity is directly proportional to the gradient of a displacement time graph. Therefore negative displacement = negative velocity.
When resolving forces what is the golden rule?
resolve forces only when they are perpendicular to the lever.
What does a clockwise force produce
Negative moment
Define Force (inc units)
Force is the interaction between two or more objects. Measured in Newtons (N)
What is Newtons 1st Law of Motion
Law of inertia: An object will remain at rest o continue to move with constant momentum in a straight line, unless it is acted upon by a net external force.
Inertia is a force - True or False
False - It is not a force
How do you calculate Angular Momentum?
Inertia (m) x Angular Velocity
What is inertia proportional to?
A Body’s mass
Define Newton’s Second Law of Motion
Law of Acceleration The rate of change of momentum is proportional to the force causing the change and takes place in the direction of the applied bet force. Force = Mass x acceleration
Define Pressure
Pressure is the measure of the distribution of force over the surface area of contact P = Force / Area
Describe the 3 different types of loading
Tensile (force < —— > ) Compressive - pushing in from both sides >——< Sheer loading