(a) What are through variables in mechanical, electrical, fluid, and thermal systems?
(b) What are across variables in mechanical, electrical, fluid, and thermal systems?
(c) Can the velocity of a mass change instantaneously?
(d) Can the voltage across a capacitor change instantaneously?
(e) Can the force in a spring change instantaneously?
(f) Can the current in an inductor change instantaneously?
(g) Can purely thermal systems oscillate?