In a CD player, the speed of the surface of the CD at the point where the laser is reading the CD must be a constant 1.30 m/s. The CD needs to vary angular speed as the laser reads at different points along the CD. The laser is 54 mm from the center. What should the angular speed be in rev/sec for the CD?

A. 3.8 rev/sec

B. 12.5 rev/sec

C. 6.3 rev/sec

D. 24.2 rev/sec

A spring is hanging vertically at equilibrium. When a mass of .5 kg is attached to the spring, the spring stretches by 2.1 cm. What is the spring constant (k) for the spring?

A. 0.43 N/cm

B. .21 N/cm

C. 4.7 N/cm

D. 2.3 N/cm