ENERGY CONSERVATION

# ENERGY CONSERVATION - nc is the rotational work done by a...

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ENERGY CONSERVATION The work–energy theorem states that the net work done on a system is equal to the change in kinetic energy of a system. For a system that does not rotate and has constant mass: W net = k = 0.5m (v 2 - v 0 2 ) The most general form of the work- energy theorem allows for the possibilities of rotation, varying mass, and varying moment of inertia, I. W net = + k Rk = 0.5mv 2 + 0.5I 2 ϖ - 0.5m 0 v 0 2 - 0.5I 0 0 2 The subscript zero represents the initial value and Rk is the rotational kinetic energy. Total external mechanical energy is the sum of all external kinetic and potential energies of the system. E = K + RK + U + RU RU is the rotational potential energy from a conservative torque. Any change in the total external mechanical energy is due to the work done by non-conservative forces and torques. These forces and torques can be internal as well as external. E = W nc + RW nc RW
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Unformatted text preview: nc is the rotational work done by a non-conservative torque. Some fraction of the total mechanical energy of a system may be converted to heat. Kinetic friction or drag forces may dissipate mechanical energy and convert that energy to heat. The total external mechanical energy may be changed by other sources of energy. Internal chemical (electromagnetic) potential energy can be transformed into heat (internal kinetic energy) as well as work (external kinetic energy) and will increase the total external mechanical energy. Our bodies and our car’s engine convert chemical potential energy to heat and produce external kinetic energy. The total energy/mass of the universe is conserved. This energy includes mechanical, nuclear, electromagnetic, and rest mass energy. Some times energy flows into a system, other times it flows out....
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