The mechanical force of contraction is generated by? a sliding of thin filaments past thick filaments

the "accordian-like" folding of thin and thick filaments

shortening of the thick filaments

the temporary disappearance of thin filaments

First answer marked as brainiest which is the correct equation describing the first law of thermodynamics? a) when the internal energy of a system changes, it equals the amount of heat added plus the work done. b) when work is done by the piston, it is equal to the heat added plus the change in internal energy of the system. c) when heat is added to the system, it is equal to the amount of work done by the piston plus the change in internal energy of the system.