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53 Cards in this Set

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Resistance Arm
resistance arm
the perpendicular distance from the fulcrum to the line of action of the resistance acting on the resistance point.
force lever
When the force arm of a lever is longer than its resistance arm, the mechanical advantage favors application of force, at the sacrifice of speed.
speed lever
When the resistance arm of a lever is longer than its force arm, the mechanical advantage favors application of speed, at the sacrifice of force.
first class lever speed or force type?
can be either – either, depending on relative position of FA, RA, and A.
first class lever
fulcrum at some location between the force point and the resistance point. eg: triceps on elbow joint. elbow=fulcrum, triceps insertion is forcepoint on olecranon, gravity = resistance point.
second class lever
resistance point at some location between force point and the fulcrum.
third class lever
force point at some location between the resistance point and the fulcrum – most common in body. muscle can be inserted near joint to produce distance and speed of movement.
Describe the force-velocity curve. How does fibre type distribution effect this curve?
Force velocity curve assesses influence of speed of shortening or movement of muscle on strength of contraction. more type II = more force. more speed = less force.
Identify the factors that can affect the strength of a muscle.
1. speed of shortening of fibres
muscular force over a range of motion (force times distance.) distance = moment arm.
isotonic muscle contraction definition and example
muscle shortening while lifting a constant load
isometric muscle contraction definition and example
no visible muscle shortening or change in angle of bones
isokinetic muscle contraction definition and example
constant speed of contraction: tension maximal over full range of motion
eccentric muscle contraction definition and example
lengthening of muscle during contraction. controlled elongation of muscles toward original resting length.
Identify the factors that affect the tension of a muscle undergoing an isotonic contraction in the body and explain how they affect tension.
tension of muscle and force it can produce effected by: initial length of fibres (able to exert most force from relaxed position – as it shortens, less tension can be exerted.), angle of pull of muscle on skeleton (there is an optimal range of angles at which muscles can apply the most force.), speed of shortening (affected by distribution of fibres also. type I or type II fibre availability can effect tension availability) + speed at which muscle can contract.
Describe muscle force-velocity relationships and muscle power-velocity relationships. How does fibre type distribution affect the shape of force-velocity curves and power velocity curves?
peak torque decreases with increased velocity.
torque is greatest at lowest speeds.
At any velocity, higher % torque is produced with higher % type two fibres.
Higher % type one = less torque.
Distinguish between muscular strength and muscular endurance.
strength = greatest amount of force that a muscle or muscle group can
produce in a single, maximal contraction.
endurance=capacity of a muscle group to
perform repeated contractions against a load for an extended time period.
third class levels force levers or speed levers?
Always speed levers - FA always less than RA.
force arm
mechanical advantage
force arm divided by resistance arm: efficiency with which a lever is able to magnify forces.
centre of gravity
point at which body may rotate freely in all directions
ability to control equilibrium
when a body is able to resist disruption of equilibrium
study of forces associated with motion
appearance of motion, movement of bodies with respect to time or precise speed and movement of body parts.
mass corrected for gravity=
kg x 9.81 m/s2
force times distance
Potential energy. Weight times height.
Kinetic energy unit
mass times velocity
Mechanical advantage
force arm divided by resistance arm
quantifies direction and forces of human movement
tendency of a body to maintain a motionless state or a state of constant velocity.
acceleration formula
force equals mass times acceleration f=ma
weight formula
mass in kg x 9.81 (acceleration caused by gravity.)
a push or a pull acting on an object.
force against a resistance, and the distance the resistance is moved.
unit of work. J= units of force multiplied by units of distance.
capacity to do work.
potential energy
energy of position, which provides the potential to do work.
potential energy formula
Potential energy is a body’s Weight (Wt) times its height above a surface. PE=(Wt)(h)
kinetic energy
energy possessed by a body as a result of linear motion
kinetic energy formula
KE= ½ mv2
the quantity of motion that an object posesses.
momentum formula
M=mv (Momentum equals mass times velocity)
a rigid bar that turns about an axis
force point
point where force is applied. In humans, this is the muscle insertion.
resistance point
the exact point on which the resistance acts
the axis of motion
force arm (FA)
perpendicular distance from the fulcrum to the line of action of the force acting on the force point.
distinguish between force and speed levers
force levers are longer levers that are better at imparting force due to their longer length. Speed levers are usually shorter, and can move faster through the same number of degrees because of their shorter length.
what is the law of conservation of mechanical energy?
the sum of potential energy plus kinetic energy is constant.