A voltage regulator is to provide a constant DC voltage Vl=10V to a load Rl from a nominal Vcc=15V supply voltage. The load can vary from 20Ω to 1KΩ. The supply voltage Vcc can vary from 13V to 16V. The op-amp can provide a maximum output current of 20mA. a)Find the βnecessary for the transistor to provide the needed current. b)Find the maximum power the transistor must dissipate.

Asolid cylinder is concentric with a straight pipe. the cylinder is 0.5 m long and has an outside diameter of 8 cm. the pipe has an inside diameter of 8.5 cm. the annulus between the cylinder ad the pipe contains stationary oil. the oil has a specific gravity of 0.92 and a kinematic viscosity of 5.57 x 10-4 m2/s. most nearly, what is the force needed to move the cylinder along the pipe at a constant velocity of 1 m/s?