M) When kicking a ball, the angular acceleration of the kicking leg is at a maximum when the lower leg is vertical and at the instant the foot strikes the ball. Calculate the joint reaction forces at the knee and muscle force exerted by the quadriceps at the instant just before the ball is kicked. At this instant, the angular velocity (w = 9rad/s) and the angular acceleration is (a = 402rad/s?). The weight of the lower leg (including the foot) is 7 kg, and the mass moment of inertia about the centre of rotation of the knee is 0.35 kg – m². The distance from the patellar tendon to the center of rotation of the knee joint is 3 cm, and the distance from the COM of the lower leg to the centre of rotation of the knee is 20 cm. Assume that during this kick, the knee centre is not moving or accelerating, the foot never touches the ground, and the quadriceps muscle only acts vertically. The X axis is aligned horizontally (positive = to he right) and the Y axis is aligned vertically (positive = upwards). ω,α Em = N F;| = F,| = N

M) When kicking a ball, the angular acceleration of the kicking leg is at a maximum when the lower leg is vertical and at the instant the foot strikes the ball. Calculate the joint reaction forces at the knee and muscle force exerted by the quadriceps at the instant just before the ball is kicked. At this instant, the angular velocity (w = 9rad/s) and the angular acceleration is (a = 402rad/s?). The weight of the lower leg (including the foot) is 7 kg, and the mass moment of inertia about the centre of rotation of the knee is 0.35 kg – m². The distance from the patellar tendon to the center of rotation of the knee joint is 3 cm, and the distance from the COM of the lower leg to the centre of rotation of the knee is 20 cm. Assume that during this kick, the knee centre is not moving or accelerating, the foot never touches the ground, and the quadriceps muscle only acts vertically. The X axis is aligned horizontally (positive = to he right) and the Y axis is aligned vertically (positive = upwards). ω,α Em = N F;| = F,| = N

University Physics Volume 1

18th Edition

ISBN:9781938168277

Author:William Moebs, Samuel J. Ling, Jeff Sanny

Publisher:William Moebs, Samuel J. Ling, Jeff Sanny

Chapter6: Applications Of Newton's Laws

Section: Chapter Questions

Problem 70P: Part of riding a bicycle involves leaning at the correct angle when making a turn, as seen below. To...

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