He-11 Mechanical Equivalent of Heat Apparatus
Aim
This Mechanical Equivalent of Heat Apparatus demonstrates that mechanical energy can be converted to an equivalent heat energy.
Apparatus
- Mechanical Equivalent of Heat Apparatus
- Multimeter
- 10Kg Weight
Mechanical Equivalent of Heat Apparatus.
Description
The apparatus is simple and accurate. Turn the crank to perform a measurable amount of work. The crank turns an aluminium cylinder. A flat nylon rope is wrapped several times around the cylinder. As the crank is turned, the friction between the rope and the cylinder is just enough to support a mass hanging from the other end of the rope. This ensures that the torque acting on the cylinder is constant and measurable. A counter keeps track of the number of turns of the crank. The work required to turn the cylinder is converted to thermal energy by the friction between the cylinder and the rope. The thermal energy is measured by monitoring the temperature of the cylinder using the embedded thermistor. The ratio between the work performed and the thermal energy produced and transmitted to the cylinder determines the mechanical equivalent of heat. With this apparatus, the equivalence of work and heat is easily established to within 5%. The thermisor is connected to an ohmeter. The resistive value of the thermistor corresponds to the temperature of the thermistor. A chart of resistance versus temperature is printed on the apparatus.