Problem 18: While exercising in a fitness center, a man lies face down on a benc

Question

Problem 18: While exercising in a fitness center, a man lies face down on a bench and lifts a weight with one lower leg by contacting the muscles in the back of the upper leg Part (a) Find the magnitude of the angular acceleration produced given the mass lifted is 11 kg at a distance of 29.5 cm from the knee joint the moment of inertia of the lower leg is 0.93 kg-m2, the muscle force is 1400 N, and its effective perpendicular lever arm is 2.95 cm. Numeric A numeric value is expected and not an expression = Part (b) How much work is done if the leg rotates through an angle of 21.5° with a constant force exerted by the muscle? Numeric A numeric value is expected and not an expression. net w

Explanation / Answer

net torque = 1400N * 0.0295m - 11kg * 9.8m/s² * 0.295m
= 9.499 N·m

total I = 0.93kg·m² + 11kg*(0.295m)² = 4.175 kg·m²

= I
9.499 N·m = 4.175kg·m² *
= 2.275 rad/s²

work done, is given by F*d:
work = * cos = 9.499 N·m * cos(21.50 )*= 8.839 J

Related Questions

Navigate

• Browse (All)
• Browse P
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.