In the figure below, two particles, each with mass m = 0.87 kg, are fastened to
ID: 2092226 • Letter: I
Question
In the figure below, two particles, each with mass m = 0.87 kg, are fastened to each other, and to a rotation axis at O, by two thin rods, each with length d = 10 cm and mass M = 1.4 kg. The combination rotates around the rotation axis with angular speed ? = 0.34 rad/s. (a) Measured about O, what is the combination's rotational inertia? (b) What is the combination's kinetic energy?
AlsoIn the figure below a cylinder having a mass of2.0kg can rotate about its central axis through pointO. Forces are applied as shown:F1=18.0N,F2=12.0N,F3=6.0N, andF4=7.0N. Also,r= 5.0 cm andR= 12 cm.
Explanation / Answer
first figure ,,,,,,,,,, a) I = 0.87*0.1^2 + 1.4*0.2^2 = 0.0647 ,,,,,,, b) rotational ke = 0.5*0.0647*0.34*0.34 = 0.003739 J,,,, second figure net torque= (6*0.5)+(12*0.12)-(18*0.12) = 2.28 (angular acceleration ) * (2*0.12*0.12*0.5) = 2.28 ,,,,(angular acceleration ) = 158.333