Rubber Band Energy Equation

We introduce a rubber band experiment that uses maxwell relations to measure changes in entropy and internal energy.

Rubber band energy equation. Khan academy is a 501 c 3 nonprofit organization. When the bands are stretched the energy is increased and the polymers untangle until they reach a local maximum of their length and a local minimum of entropy. Hopefully you said there s a lot of epe and no ke. When the rubber band is released the potential energy is quickly converted to kinetic energy.

1 where t is the temperature s is the tension u is the internal energy of the rubber band s is its entropy and l is its length. Rubber band at rest and the energy it holds. F force in newtons. W elastic potential energy in joules.

When the rubber band is released the potential energy is quickly converted to kinetic motion energy. The cross linked polymers of a rubber band begin in a chaotic low energy tangled state. The energy the rubber band has stored is related to the distance the rubber band will fly after being released. It can be stretched by up to a factor of 10 from its original length and when released returns very nearly to its original length.

When released the entropy rapidly increases until they tangle again compressing the rubber. Estimate the epe and ke before the student lets go of the rubber band. 140 energy foundations for high school chemistry 2013 american chemical society lab tips various lab equipment items could be placed in the laboratory area to inspire students as they design their method in step 6 to test the stretch contraction of the rubber band as it is heated. Elastic potential energy force x distance of displacement.

This is equal to one half the mass of the rubber band multiplied by its velocity in. Elastic potential energy is equal to the force times the distance of movement. You will investigate the relationship between the potential energy and kinetic energy in this system by seeing how far the rubber band flies when it is stretched to different lengths. Rubber is a member of a larger class of materials called elastomers and it is difficult to overestimate their economic and.

Look at the following picture. This can be repeated many times with no apparent degradation to the rubber. Once the rubber band is done unwinding the cart will slow down due to the kinetic energy of the cart transferring to dissipated thermal energy from friction. Construct use and present arguments to support the claim that when the kinetic energy of an object changes energy is transferred to or from the object.

Theoretical background the thermodynamic identity for a rubber band is du tdsþ sdl.