Long cylindrical steel rods (rho = 7833 kg/m3 and cp = 0.465 kJ/kg·°C) of 8 cm diameter are heat-treated by drawing them at a velocity of 2 m/min through an oven maintained at 900°C. If the rods enter the oven at 30°C and leave at a mean temperature of 540°C, determine the rate of heat transfer to the rods in the oven.

The heat transfer rate Q' is 311.26 kJ / s.

Explanation:

                                  d = 8 cm = 8 / 100 = 0.08 m

                                  m = (πd^2 / 4) l ρ

                                  m = (π (0.08)^2 / 4) (2)(7833)

                                 m = 78.75 kg.

The heat transfer Q is

                                  Q = m c (T2 - T1)

                                      = (78.75) (0.465) (540 - 30)

                                      = 18676 kJ  

The heat transfer rate Q' is

                                  Q' =  Q / t

                                       = 18676 / 60

                                  Q' = 311.26 kJ / s.

a solenoid is created by wrapping a l = 90 m long wire around a hollow tube of diameter d = 4.5 cm.   the wire diameter is d = 0.9 mm.   the solenoid wire is then connected to a power supply so that a current of i = 9 a flows through the wire.

randomized variablesl = 90 m

d = 4.5 cm

d = 0.9 mm

i = 9 a                                          

write an expression for the number of turns, n, in the solenoid. you do not need to take into account the diameter of the wire in this calculation.

calculate the number of turns, n, in the solenoid.

write an expression for the length of the solenoid (l2) in terms of the diameter of the hollow tube d.

calculate the length of the solenoid (l2)   in meters.

calculate the magnitude of the magnetic field at the center of the solenoid in teslas.

explanation:

0.55x745.7j and a calculator