Question
9) A solid copper sphere of radius r = 1 cm and mass density p = 8.4 g/cm^3. The sphere rotates about its longitudinal axis, which is vertically oriented along the z-axis. If the sphere is rotating with frequency f = 60 Hz, calculate its angular momentum. Choose one of the closest answers shown below. a) L = 1.27 x 10^-4 kg*m/s; b) L = 4.33 x 10^-66 kg*m/s; c) L = 33 x 10^-2 kg*m/s; or d) 433 x 10^-6 kg*m/s; 10) In the problem above, calculate the kinetic energy of the sphere's rotation. Choose one of the closest answers shown below. a) KE = 2.38 x 10-2 J; b) KE = 127 x 10^-2 j; c) KE= 27.3 x 10^-2 J; or d) KE = 0.0048 J.
Explanation / Answer
a) ? = 2pi/60 = 0.105 for a sphere I=2/5mr2
L = I*? = .4mr
