Force KIN3323 Biomechanics Unit objectives At the completion of this unit, students should be able to: EIEIEI EIEIEIEIEIEIEIEIEIEIEIEIEIEI EIEIEIEIEIEIEIEIEIEIEIEIEIEIEIEI EIEI Describe force and its effects on the objects acted on by the force Describe contact force vs. non-contact force Describe the characteristics of the reaction force Describe magnitude, direction, point of application, and line of action of the contact force Describe magnitude, direction, point of application, and line of action of the gravitational force Calculate the magnitude of gravitational force acting on an object with known mass Describe 4 unique qualities of a muscle tissue Describe the structural organization of the muscle Describe how muscles produce tension (force) Describe motor unit and its characteristics Describe the size of the motor unit for the muscles that perform delicate vs. gross movements Describe the difference between type | and II muscle fibers Describe how the action potential results in muscle contraction Describe activation threshold for Type I and II muscle fibers and how they affect the order of motor unit recruitment Describe Henneman's size principle List the factors that affect the ability of the muscle to produce force Describe how the max force produced by the muscle is affected by 0 Physiological crosssectional area of the muscle Pennation angle Distribution of muscle fiber type Length of the muscle relative to the resting length Contraction velocity 0 Rapid eccentric contraction of the muscle before the concentric contraction Describe how and why we break forces into components Describe the effects of muscle force components (rotary, stabilizing, dislocating components) at the joint based on the figure depicting the joint and the muscle force Describe the factors that increase the sliding force (force component along the surface) Describe the friction and normal force component of the reaction force Describe the effects of the friction force Describe static friction Describe coefficient of static friction Describe the factors that increase/decrease the normal force Describe how the coefficient of static friction and normal force affect the static friction Describe the relationship between friction and static friction Describe how much sliding force is needed for the two surfaces to start sliding against each other Calculate friction and normal force from the magnitude and direction of force Calculate static friction and determine if the slip will occur based on the calculated values Describe resultant vs. net force Describe how to calculate the sum of 2 or more forces Calculate the sum of 2 or more forces Describe the effects of the lateral forces acting on the patella on patellofemoral compressive stress Describe the clinical factors that increase the lateral force acting on the patella OOOO Describe the effects of knee flexion angle and quadriceps force produced resultant on the patellofemoral compressive stress Describe the strategy to alleviate the Symptoms of the patellofemoral pain syndrome based on the analysis of the re3ultant force