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Newton’s laws of motion
Published in Paul Grimshaw, Michael Cole, Adrian Burden, Neil Fowler, Instant Notes in Sport and Exercise Biomechanics, 2019
The moment of inertia of an object refers to the object’s ability to resist rotation. The larger the moment of inertia, the more the object will resist rotation. Similarly, the smaller the moment of inertia of an object, the less will be its resistance to start, stop or change its rotational state (Figure C7.1). The moment of inertia is calculated from the distribution of mass (m) about an axis of rotation (r). It can be expressed mathematically as I = m × r2. The moment of inertia of a body is related to a specific axis of rotation and there will be different moment of inertia values for each axis that the body is rotating about. For example, there may be a moment of inertia of the whole body about a longitudinal axis or about an anterior–posterior axis. Also, moment of inertia can be expressed for individual parts or individual segments of a body (e.g. the upper leg can have a moment of inertia about the hip joint axis of rotation or the lower leg a moment of inertia about the knee joint axis of rotation).
General introduction
Published in Adedeji B. Badiru, Handbook of Industrial and Systems Engineering, 2013
Centripetal force is defined as the force acting on a body in curvilinear motion that is directed toward the center of curvature or axis of rotation. Centripetal force is equal in magnitude to centrifugal force but in the opposite direction. FcP=-Fc=mv2r
Stress and Strain Analyses
Published in Joseph W. Freeman, Debabrata Banerjee, Building Tissues, 2018
Joseph W. Freeman, Debabrata Banerjee
The Moment of Inertia is the resistance of an object to rotation. So if you let y = c, σmax=Mc/IFor any distance y, σy=−My/I, the negative sign comes from σx=−y/c(σmax)In this equation:Stress is compressive σ x < 0 and y > 0 above neutral axis M = positionStress is tensile σ < 0 and M is negativeThe moments of inertia have been defined for many common shapes. They are listed in Table 1.1.
Evaluation of maximum thigh angular acceleration during the swing phase of steady-speed running
Published in Sports Biomechanics, 2023
Kenneth P. Clark, Laurence J. Ryan, Christopher R. Meng, David J. Stearne
Finally, the findings of this study may provide insight into optimal strategies for training interventions. Angular acceleration is proportional to torque and inversely proportional to the moment of inertia due to Newton’s second law for rotation. Thus, the functional capability to produce the larger angular acceleration values required at higher speeds is largely determined by the runner’s maximum torque capacity at the hip joint. This concept is supported by research demonstrating that measurements of hip flexion power and moments are positively related to sprinting speed (Copaver et al., 2012; Nagahara et al., 2020). Therefore, interventions aimed at improving an athlete’s hip torque capacity (and thus maximum thigh angular acceleration), such as resistance training to increase hip flexor strength (Deane et al., 2005) or use of wearable resistance during sprinting (Macadam et al., 2020), may be warranted.
Athlete body composition influences movement during sporting tasks: an analysis of softball pitchers’ joint angular velocities
Published in Sports Biomechanics, 2022
Kenzie B. Friesen, Arnel Aguinaldo, Gretchen D. Oliver
Theoretically, segment motion can be greatly influenced by body composition. Mass moment of inertia is the mass of a segment multiplied by the radius of gyration (distribution of mass away from the axis of rotation) and is considered the measure of a segment to resist change in angular velocity. Therefore, it can be presumed that the pitchers who are larger and carry additional body fat may have increased segmental mass moment of inertia. Consequently, it is predicted that body fat presence may alter joint angular velocities among softball pitchers. Therefore, the purpose of this study was to examine the relationship between peak joint angular velocities and pitch velocity and to examine how pitchers among a high body-fat and healthy body-fat percentage (BF%) group may differ in joint angular velocity during the softball pitch. It was presumed that the pitchers with a higher body-fat percentage would reach greater joint angular velocities over a longer period. It was also hypothesised that joint angular velocities would be positively correlated with pitch velocity.