When a fan is at its highest setting, the fan blade is rotating at 150 Hz. When the fan is turned down to its next lowest setting, the fan blade uniformly decelerates at 12 cycles/s2 until it reaches 60 Hz. Through how many cycles does the fan blade rotate over this interval

Asolid round steel rod 6.25 mm in diameter and 375 mm long is rigidly bonded to the end of solid square brass rod 25 mm on a side and 300 mm long. the geometric axes of the bare are along the same line. an axial tensile force of 5.4 kn is applied at the extreme ends of the assembly. for steel e = 200 gpa and for brass e = 90 gpa. determine the total elongation for the assembly.