While exercising in a fitness center, a man lies face down on a bench and lifts a weight with one lower leg by contracting the muscles in the back of the upper leg. The weight has mass 13.5 kg, and is a distance of 28.0 cm from the knee joint. The moment of inertia of the lower leg is 0.900 kg m², the muscle force is 1490 N, and its effective perpendicular lever arm is 3.45 cm. Find the magnitude of the angular acceleration a of the weight. 9.9 rad/s? How much work W is done if the leg rotates through an angle of 25.0° with a constant force exerted by the muscle? W = 7.21 Question Credit: OpenStax College Physics A stick is resting on a concrete step with of its total length L hanging over the edge. A single ladybug lands on the end of the stick hanging over the edge, and the stick begins to tip. A moment later, a second, identical ladybug lands on the other end of the stick, which results in the stick coming momentarily to rest at 0 = 46.5° with respect to the horizontal, as shown in the figure. If the mass of each bug is 2.92 times the mass of the stick and the stick is 18.7 cm long, what is the magnitude a of the angular acceleration of the stick at the instant shown? Use g = 9.81 m/s? rad/s? Figure is not to scale.

While exercising in a fitness center, a man lies face down on a bench and lifts a weight with one lower leg by contracting the muscles in the back of the upper leg. The weight has mass 13.5 kg, and is a distance of 28.0 cm from the knee joint. The moment of inertia of the lower leg is 0.900 kg m², the muscle force is 1490 N, and its effective perpendicular lever arm is 3.45 cm. Find the magnitude of the angular acceleration a of the weight. 9.9 rad/s? How much work W is done if the leg rotates through an angle of 25.0° with a constant force exerted by the muscle? W = 7.21 Question Credit: OpenStax College Physics A stick is resting on a concrete step with of its total length L hanging over the edge. A single ladybug lands on the end of the stick hanging over the edge, and the stick begins to tip. A moment later, a second, identical ladybug lands on the other end of the stick, which results in the stick coming momentarily to rest at 0 = 46.5° with respect to the horizontal, as shown in the figure. If the mass of each bug is 2.92 times the mass of the stick and the stick is 18.7 cm long, what is the magnitude a of the angular acceleration of the stick at the instant shown? Use g = 9.81 m/s? rad/s? Figure is not to scale.

Glencoe Physics: Principles and Problems, Student Edition

1st Edition

ISBN:9780078807213

Author:Paul W. Zitzewitz

Publisher:Paul W. Zitzewitz

Chapter5: Displacement And Force In Two Dimensions

Section: Chapter Questions

Problem 82A

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