Estimate the radiant heat transfer from the wire in Watts.You can assume that the surface temperature of the wire is approximately 800°C and that the wire is a thermal black body.

Problem 1:

Toasters, blow dryers, and electric space heaters do their jobs via electric resistance heating: when electricity flows through a high-resistance wire, the temperature of the wire goes up, and heat is dissipated from the wire to the surroundings. A particular toaster uses 20 feet of a Nichrome resistance wire to cook toast.   The diameter of the wire is 0.0265 inches.

 

  1. Estimate the radiant heat transfer from the wire in Watts.You can assume that the surface temperature of the wire is approximately 800°C and that the wire is a thermal black body.
  2. About how much current will this toaster use when connected to a 110 V power source?

 

Problem 2:

 

Since it is fall, the days are getting shorter so I started running indoors on an elliptical trainer.  It has a readout that states the number of RPMs of its internal flywheel and how many Watts I am generating to turn the flywheel while exercising.  Typically I put out an average of 400 W for 25 minutes while the flywheel rotates at 120 cycles per minute.

 

  1. calculate the torque applied to the flywheel assuming all of it is transferred with no losses due to friction, air resistance, mechanical compliance, etc.