**Measurement
and Calculation about the furnace**

For the calculation, some parameters of the furnace were collected. Here are the data:

The melting point of copper is 1083.4 ¢J

Density
of Copper: 8900 kg/m^{3}

The melting point of iron is 1530 ¢J

Density
of iron: 7830 kg/m^{3}

Parameter of the furnace:

Downward force: 4.55kg=4.55x9.81=44.636N

Upward force: 13.64kg= 13.64x9.81=133.808N

Max. Torque =RxF

=(740+80.5)x10^{-3}(133.808)

=109.789Nm

Rotational speed: about 3 sec. for
100^{o}

=1/10.8 rps= 5.56rpm

i.e.=

Power required: Torque x Rotational speed

=(109.789)(0.628)

=68.982W

Since the force that needs to move the furnace downward is smaller than upward due to the shifting of the centre of gravity. That means if we want to rotate this furnace, the required power is at least 70W.

The minimum diameter of shaft to resist the rotation of furnace:

Yield strength of the steel(£n): 250-690 MPa

where

So the minimum diameter of the shaft is 13.078mm, but to ensure the shaft can resist the rotation as a factor safety, we use the diameter of 20mm shaft.