Biomech Exam 2 Flashcards
What does lever arm mean?
The distance between the axis of rotation and the point of force application.
What is Torque?
The turning effect of a force
True or false? Only perpendicular force can produce torque.
True, you can apply force at an angle but it will not be as effective as applying perpendicular force on the rigid body.
True or false? The direction of effective torque will not affect the direction of angular acceleration.
False, Angular acceleration will go the same direction as net torque or effective torque.
True or false? In order to be effective a torque has to be applied over time.
True
On a torque time curve, what variables can be seen on the chart?
Peak Torque = highest magnitude
Increase in Slope = Rate of Torque development
Decrease in Slope = Rate of Torque fatigue
The area under the curve = Angular Impulse
What is the symbol for Angular Impulse
Delta H
What is an effective mechanical advantage?
Perpendicular Distance A / Perpendicular Distance B
When perpendicular distance A is larger than distance B
If you wanted to apply greater torque would it best to apply it at a farther distance from the axis of rotation? Would this be a mechanical advantage or disadvantage?
Yes, to create greater torque applying force farther from the axis of rotation would be more advantageous than applying it closer.
What is an effective mechanical disadvantage?
When perpendicular distance A is shorter than perpendicular distance B.
What is energy?
The state of matter that makes things change or has the potential to make things change
Mechanical energy has two subdivisions, name both and their related subdivisions too.
POTENTIAL ENERGY, gravitational energy, and strain energy
KINETIC ENERGY, Linear, and angular
What is the difference between gravitational and strain potential energy?
Gravitational relates to the energy associated with the position, where the higher the object is the more GpE is created.
Strain relates to the energy associated with deformation where the more it is pulled or changes shape the more energy will be made, EX. resistance band
True or false?
Linear and Angular kinetic energy refers to the object in motion and where velocity is more impactful to its generation of energy.
True
What is the conservation of energy?
Energy cannot be created nor destroyed, it can be moved from one place to another or changed from one form to another.
What is the definition of work?
The process by which we either increase or decrease the amount of energy in a system.
What is the formula for work?
W = Force x displacement
What is the difference between positive and negative work?
Positive work means generating energy or putting more energy into a system. (Positive force times positive displacement / negative force times negative displacement)
Negative work means absorbing energy or taking energy out of a system. (Positive force times negative displacement / Negative force times positive displacement)
True or false?
Energy is a vector.
False, energy is a scalar.
What is the equation for work regarding angular kinetics?
W = Torque x angular displacement
(Torque and force are the same)
What is the equation for mechanical energy expenditure?
MEE = +W + |-W|
What is the equation for efficiency?
Efficiency = (Output / input) x 100
or
Efficiency = (Mechanical energy expended / Metabolic energy) x 100
True or false.
Some activities are 100 percent efficient.
False, there are no activities that are 100 percent efficient.
Describe where the center of mass will be for walking gait.
The center of mass will be at its low point at initial contact and toe-off, whereas the center of mass will be at its high point during midstance.
Describe where the center of mass will be for running gait.
The center of mass will be at its high point at initial contact and toe-off whereas the center of mass will, be at its low point during midstance.
What is the definition of power and its linear and angular formula?
Power is the time rate of doing work, and how much force you can develop while moving quickly.
P = W/ delta time
P = Force times velocity
P = Torque times angular velocity
What is the difference between a perfectly elastic collision and a perfectly inelastic collision?
A perfectly elastic collision will conserve kinetic energy while a perfectly inelastic collision does not conserve kinetic energy.
What is the coefficient of restitution?
How bouncy a ball is and in sports the governing body limits the coefficient of restitution.
What is the effective mass?
How much mass is involved in the collision.