Many 2.5-in-diameter (6.35-cm) computer hard disks spin at a constant 7200 rpm operating speed. the disks have a mass of about 7.50 g and are essentially uniform throughout with a very small hole at the center.

if they reach their operating speed 2.50 s after being turned on, what average torque does the disk drive supply to the disk during the acceleration?

Explain the difference laminar and turbulent flow. explain it with the shear stress and the velocity profiles.

If a particle moves along a path such that r : (3 sin t) m and ? : 2t rad, where t is in seconds. what is the particle's acceleration in m/s in 4 seconds? a)- 16.43 b)- 16.29 c)- 15.21 d)- 13.79

For the closed feedwater heater below, feedwater enters state 3 at a pressure of 2000 psia and temperature of 420 °f at a rate of ix10 ibhr. the feedwat extracted steam enters state 1 at a pressure of 1000 psia and enthalpy of 1500 btu/lbm. the extracted er leaves at an enthalpy of 528.7 btu/lbm steam leaves as a saturated liquid. (16) a) determine the mass flow rate of the extraction steam used to heat the feedwater (10) b) determine the terminal temperature difference of the closed feedwater heater