Two forces 40 N and 30 N act at right angles to each other on a particle. The resultant force is

18) Heat transfer occurs due to _____ difference

19) Density of mild steel is _____ kg/cubic meter

20) A _____ die, both cutting and non-cutting operations are done in a press station in one stroke of ram.

21) H7 f7 represents a _____ fit.