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### 53 Cards in this Set

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 RA 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 Torque: 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. FA 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 balance ability to control equilibrium stability when a body is able to resist disruption of equilibrium kinetics study of forces associated with motion kinematics appearance of motion, movement of bodies with respect to time or precise speed and movement of body parts. weight mass corrected for gravity= kg x 9.81 m/s2 work force times distance PE Potential energy. Weight times height. Kinetic energy unit joules Momentum mass times velocity Mechanical advantage force arm divided by resistance arm biomechanics quantifies direction and forces of human movement inertia 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.) force a push or a pull acting on an object. work force against a resistance, and the distance the resistance is moved. joule unit of work. J= units of force multiplied by units of distance. energy 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 momentum the quantity of motion that an object posesses. momentum formula M=mv (Momentum equals mass times velocity) lever 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 fulcrum 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? (PE+KE)=C the sum of potential energy plus kinetic energy is constant.