- #1
C. Lee
- 29
- 1
I am now reading Lagrange's equations part in Taylor's Classical Mechanics text.
It says:
When a system of interest involves constraint forces, F_cstr, and all the nonconstraint forces are derivable from a potential energy(U), then the Lagrangian for the system L is L = T - U, where U is the potential energy for the nonconstraint forces only, and thus this definition of L excludes the constraint forces.
Here's the question: How do we know that U in L = T - U is the potential energy for the nonconstraint forces only? Shouldn't it have contribution from constraint forces if some of constraint forces are conservative?
It says:
When a system of interest involves constraint forces, F_cstr, and all the nonconstraint forces are derivable from a potential energy(U), then the Lagrangian for the system L is L = T - U, where U is the potential energy for the nonconstraint forces only, and thus this definition of L excludes the constraint forces.
Here's the question: How do we know that U in L = T - U is the potential energy for the nonconstraint forces only? Shouldn't it have contribution from constraint forces if some of constraint forces are conservative?